Detection of Delta 9-Tetrahydrocannabinol (THC) and Metabolites in Ham using Tandem Mass Spectrometry

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Date
2002-08
Authors
Abdul Manaf, Normaliza
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Abstract
Drug abuse has been recognised as a widespread problem in this country since the 1980s and has been identified as one of the major problems that threatens national security. Urine testing is the standard approach in investigating the use of i~licit drugs by individuals but this method has shown several pitfalls. On the other hand, hair has been proposed as a marker of past chronic drug intake, free from enzymatic metabolism, difficult to cheat, proportional to drug ingestion, easy to collect and the sample is stable at room temperature for a long period of time. Based on these reasons, hair samples can be used to support analysis ~'esults or as an alternative to other cOriventional sample analysis. Therefore, the aim of this study is to develop and optimised a method for cannabis detection in urine and hair and establish a correlation if any, between THC and its metabolites. Hair samples were decontaminated with dichloromethane and then finely cut with a pair of scissors. Samples were hydrolysed with 11.8 N KOH in the presence of internal standards d3-THC and d3-THCCOOH for 30 minutes at 37°e. Samples were then allowed to cool to room temperature, glacial acetic acid was added and samples were extracted twice with hexane/ethyl acetate and derivatised with MSTF A. A benchtop GCINfSINIS system based on an ion trap with electron impact ionisation was used. Detection using MSIMS mode was performed with the m1z 386 as the precursor ion for THC and the mJz 371, mJz 315 and mJz 330 were monitored for quantitative purposes while ion mJz 389 was used for the d3-THe. The ion m1z 371 was used as a precursor ion for 11-0H-THC and THCCOOH and mJz 374 was identified as the precursor ion for the d3-THCCOOH. The monitoring ions for ll-OH-THC and THCCOOH were m1z 305, m1z 289 and mJz 265. The calibration curves were linear with regression coefficients greater than 0.997. Recovery and reproducibility were assured. The limit of detection for THC and THCCOOH were 20 pg/mg and 10 pglmg for 11-0H-THe. Twenty-five hair samples from subjects under supervision were cut into 2 segments. The 50 segments obtained were examined for concentration of cannabinoid compounds. Hair concentrations range from 0.039 to 0.184 nglmg and 0.020 to 0.919 nglmg for THCCOOH and THC in hair measuring 1 cm from the scalp. Hair concentrations range from 0.024 to 0.918 nglmg and 0.027 to 0.153 nglmg for THC and THCCOOH respectively in hair measured beyond 1 cm from the scalp. No correlation was observed between THCCOOH urinalysis and THC in hair. The correlation between THC and THCCOOH in hair also could not be observed which indicates that a dose-concentration relationship does not exist either for THC or THCCOOH in hair. As a conclusion, the GCIMSIMS method with its good selectivity and high sensitivity could facilitate one to obtain accurate and reliable data in order to evaluate the drug history in addicts.
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Tetrahydrocannabinol , Metabolites
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