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.
Description
Keywords
Tetrahydrocannabinol , Metabolites