SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M21
IMPROVED GCMS ANALYSIS OF THC IN SALIVA
Charles R. Lyle, Matthew P. Clabaugh, F. Roark Galloway*: Shimadzu Scientific Instruments, Columbia,
MD; Nadina Giorgi: Redwood Toxicology Laboratory, Santa Rosa, CA
One ofthe most challenging GCMS applications is the determination ofTHC in saliva. Detection for THC
at low ppb [nglml] levels is required due to several factors including; I) rapid elimination ofTHC in saliva
from time of exposure, 2) low amount of drug for 'active' dose and 3) small sample volume available at
time of collection. This application demonstrates an example of how the Shimadzu GCMS QP-2010 can
provide the instrument performance necessary to complete this challenging analysis. Samples were
collected using the Quantisal saliva collection kit. Extractions are performed by extraction with
hexane:ethyl acetate [9:1] with 3 % acetic acid. Derivatization is completed using 50 uL BSTFA to form
the trimethylsilane derivative. 1.0 uL of sample extract is injected for analysis. Using the standard SPL­
2010 split/splitless injection port on the GC-2010 as a high pressure injector, the method was performed
with a splitless injection using a Restek 3.4mm. id. SIL TEK liner. With high-pressure injection of 175 kPa,
fast temperature ramping of35 C/min and high column flow rate, the peaks eluted from the column into the
mass spectrometer ion source in less than 3.00 minutes. These results were obtained using a 15m X
0.25mm X .25 urn phase DB-IMS column. Calibration from 1.0 25 ppb THC produced a linearity
coefficient of 0.9999 by internal standard calculation using THC-D3 at 12.5 ppb. Preliminary LOQ is
determined to be 0.25 ppb. Precision at 3.0 ppb THC is 5.97%.
1.0 ppb THC [TMS] Standard Calibration, 1.0 - 25 ppb THC
AnaR.tliu
2.
,.
y2 = 0.99986
Keywords: THC, Saliva, GCMS
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