Targeted of cannabinoids in hair and androgens in saliva and untargeted profiling of the effects of exercise

Student thesis: Doctoral Thesis

Abstract

The thesis is made up of four chapters. The first chapter is the general introduction to prepare biological samples for analysis, including extraction methods, derivatization and LC-MS instrumentation, including separation techniques. In addition, description of metabolomics approaches which are deployed in order to determine and/or quantify any changes to the metabolites which occur within a biological system in response to different stimuli such as diet, lifestyle and physical activity. The second chapter describes the quantification of cannabinoids in human hair through derivatization and liquid chromatography-tandem mass spectrometry. Cannabinol (CBN), Δ9-Tetrahydrocannabinol (THC) and its main metabolite 11nor-Δ9- Tetrahydrocannabinol carboxylic acid (THC-COOH) which are the most popular indicators of cannabis use. The use of this drug is widespread around the world and causes a serious social and health problems. In this study, a method based on solid-phase extraction (SPE) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS) was developed and validated. In this procedure, hair samples were extracted and derivatized with 2fluoro-1-methyl pyridinium-p-toluenesulfonate (FMP-TS) before injecting into the LC-MS-MS. The method showed excellent linearity with a coefficient of determination (r2) better than 0.99 for the analytes of interest. The extractionrecovery was between 81% and 105 % for all compounds. The limit of detection (LOD) and quantification (LOQ) were 2 and 20 pg/mg respectively for both CBN and THC and was 0.1 and 0.2 pg/mg for THC-COOH. Intra- and inter-assay precision were always lower than 4% and 11%, respectively, for these cannabinoids. Whereas the intra- and inter-assay bias were between (14% and 18 %) and (15 and -12 %), respectively.Twenty-seven hair specimens from cannabis consumers were investigated using the optimized and validated method. Ultimately, CBN and THC were detected in all specimens, whereas THC-COOH was quantified in 13 specimens. Unlike CBN and THC, THC-COOH was semi-quantifiable (all values less than the limit of quantification (LOQ), but more than the limit of detection (LOD)) in 3 samples and was not detected in 11 samples. The levels of CBN, THC and THC-COOH on average were (0.022-2.562 ng/mg), (0.049-0.431 ng/mg) and (0.222-4.867 pg/mg) respectively. The median levels were (0.054 ng/mg), (0.087 ng/mg) and (0.34 pg/mg) for CBN, THC and THC-COOH respectively. Detection at least of THCCOOH metabolite in hair, especially in routine work seems to be compulsory in addition to THC and other main cannabinoids in order to distinguish between active ingestion and passive exposure.In the last decade, high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) combined with electrospray ionization (ESI) has beenwidely used for determining low concentrations of steroids, and derivatization has often been employed to enhance detection. The third chapter describes the development of a derivatization method for quantification of testosterone and dehydroepiandrosterone in saliva samples from young professional soccer players, pre- and post-Training, using tandem mass spectrometry. In the present study, endogenous steroids were extracted using a Strata-XL polymeric reversephase cartridge. The isolated steroids were reacted with 2-hydrazino-1- methylpyridine (HMP). A liquid chromatography-tandem mass spectrometry (LCMS/MS) was used in a positive mode with multiple reaction monitoring (MRM) for the quantification of testosterone (T) and its biosynthetic precursor, dehydroepiandrosterone (DHEA), in saliva samples collected from twenty young Saudi professional soccer players. The extraction recovery during the pretreatment was >89% and gave
Date of Award26 Sep 2019
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorDavid Watson (Supervisor) & Ruangelie Edrada-Ebel (Supervisor)

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