SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A81
PHENMETRAZINE OR EPHEDRINE FOOLED BY LIBRARY SEARCH
Sarah M. Wille*, Carlos H. Van Peteghem, Willy E. Lambert
Laboratory of Toxicology, Ghent University, Harelbekestraat 72, B-9000 Gent, Belgium
Phenmetrazine, a central nervous system stimulant, currently abused as an anorectic agent, was positively
identified by library search after injecting a methanolic extract of an ephedrine containing powder using
different GC-MS configurations. Phenmetrazine is a controlled substance as described in the UN
Convention of Psychotropic Substances 1971, while ephedrine is used in over-the-counter medications as a
vasoconstrictor. However, very recently, the Food and Drug Administration issued a final rule prohibiting
the sale of dietary supplements containing ephedrine alkaloids because such supplements present a health
risk.
GC-MS analysis of a methanolic extract of the herbal product containing ephedrine resulted in a peak with
a nearly identical retention time as ephedrine but identified as phenmetrazine after a library search. It is
known that formaldehyde contamination in solvents such as methanol can result in conversion of
ephedrine-like compounds. Ephedrine reacts with formaldehyde to form 3, 4-dimethyl-5-phenyl-1, 3­
oxazolidine with a similar molecular weight as phenmetrazine (1). The fragmentation pattern is also
similar because both chemical structures differ only in the position of one carbon unit. Thus, library
searches alone can lead to erroneous conclusions. Experiments using a HP 7683 cold on-column- HP
6890GC-HP 5973 MSD configuration and a split injector in combination with a 3400 Varian GC-Finnigan
Magnum ion-trap MSD demonstrated that high injection temperatures influence the conversion speed. This
was evidenced by injection of a freshly made ephedrine standard in methanol using injector temperatures
from 60 up to 300°C.
Attention should be paid to the possibility of chemical and/or thermal conversion of analytes in a sample
and/or in the GC-injector, as this can lead to interpretation difficulties and erroneous identification of
analytes in a toxicological screening. As demonstrated by this case, ephedrine-containing samples are of
particular interest in view of the judicial implications.
(I) Lewis RJ et aI., J. Foresic ScL, 45,898-901 (2000).
Keywords: GC-MS, Ephedrine, Conversion.
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