SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A47
STABILITY OF PLASMA ACETALDEHYDE DETERMINED BY GAS CHROMATOGRAPHY­
POSITIVE ION CHEMICAL IONIZATION-MASS SPECTROMETRY
Meng Chen"', David M. Andrenyak, David E. Moody and Rodger L. Foltz. Center for Human Toxicology,
Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah 84112.
Simultaneous abuse of drugs and alcohol is common. Acetaldehyde is a metabolite of ethanol that
accumulates when ethanol is taken with disulfiram and in many individuals with genetic variants in alcohol
dehydrogenase and lor aldehyde dehydrogenase. Analysis of acetaldehyde is considerable difficult due to
the volatility and various factors, such as enzymatic and nonenzymatic oxidation. Most previously
published methods require immediate on-site handling of specimens to allow analysis. A goal of this work
was to develop a method where samples can be collected as plasma, stored and shipped for off-site
analysis. A novel method was developed for the determination of acetaldehyde in human plasma that
utilizes a simple liquid-liquid extraction procedure and gas chromatography-positive ion chemical
ionization-mass spectrometry (GC-PCI-MS). Using acetaldehyde-dt as internal standard, both acetaldehyde
and acetaldehyde-d 4 were derivatized directly in plasma with 2, 4-dinitrophenylhydrazine in hexane solvent
at room temperature. The derivatized- acetaldehyde and acetaldehyde-d 4 were extracted into hexane. After
centrifugation, an aliquot of supernatant was transferred to an autosampler vial for analysis. A GC capillary
column was used for the separation of the derivatives, which were subsequently ionized with ammonia
reagent gas and analyzed by MS. The GC oven temperature was initially set at 120'C and increased to
300'C at 20'C Iminute. Run time for each injection was 10 minutes. MS source and quadruple temperatures
were set at 200 and 150 'C, respectively. The prominent ions at m/z 242 and 246 for acetaldehyde and
acetaldehyde-dt. respectively, were analyzed by selected ion monitoring. The lower limit of quantification
was 0.3 j.tg/mL in 0.5 mL of plasma and the linearity in 4 assays was ~=0.998, over a range from 0.3 to 20
j.tglmL. When intra- and inter-assay precision and accuracy were evaluated at concentrations of 0.75, 8 and
15 j.tglmL, mean measured concentrations did not deviate more than 14% from the target and coefficient of
variance did not exceed 4%. After derivatization, the extracts of acetaldehyde and acetaldehyde-dt were
found to be stable for up to 117 hrs in autosampler vials at room temperature. This method is simple
because of: no need for protein precipitation; single step in liquid-liquid solvent extraction; no
concentration steps, such as drying supernatant and reconstitution. The method was used to study the
stability of acetaldehyde in human plasma. In conclusion, this simple and reliable method appears to be
useful in toxicology and other researches. The research is supported by NIDA Contract NO 1 DA-3-8829.
Key Words: Acetaldehyde, GC-MS, Stability.
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