SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A25
A RAPID METHOD FOR MEASURING ANTI-DEPRESSANTS IN POSTMORTEM BLOOD
USING DUAL COLUMN LIQUID CHROMATOGRAPHY MASS SPECTROMETRY
Jason H. Sklerov'
Office of the Armed Forces Medical Examiner, Division of Forensic Toxicology, Armed Forces Institute of
Pathology, Rockville, MD, U.S.A.
A dual column, liquid chromatography mass spectrometry method was developed for the analysis of eleven
anti-depressants and metabolites in 200uL of postmortem blood. Sample preparation consisted of internal
standard addition, protein precipitation, and microfiltration. Filtrates were injected onto an extraction
column (Oasis® HLB, 20 x 2.1mm, dp=25um) and washed with deionized water, 20% acetonitrile, at
3mLlmin. The trapped analytes were backflushed through a 10-port switching valve onto an analytical
column (Zorbax® SB-CI8, 30 x 2.1mm, dp=3.5um) using a gradient of acetonitrile (20-80%) and 0.1%
formic acid at a flow rate of O.5mLlmin. The positive, pseudomolecular ions of imipramine, desipramine,
amitriptyline, nortriptyline, fluoxetine, paroxetine, fluvoxamine, trimipramine, N-desmethyl-trimipramine,
clomipramine, and N-desmethyl-clomipramine were monitored following electrospray ionization. Overall
instrumental analysis time was 11 minutes per sample including extraction and detection. Sample
carryover, assessed by area% of signals in blank injections, was < 1.4% by the use of both a needle wash
phase and injector programming. Linear ranges varied within a 0.025-lmg/L range and the online
extraction recovery was between 75-105%. Additional time savings could be gained by the direct injection
of diluted plasma, however, due to the inconsistencies in sample collection and the potential for signal
suppression, a protein precipitation step was adopted for this work.
Keywords: Anti-depressants, Dual-column, LC/MS
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