Page 47 - Advances in Forensic Applications of Mass Spectrometry - Jehuda Yinon

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in plasma. The described and exemplified procedure allows simultaneous,
fast, and specific detection of most of the toxicologically relevant drugs
(several thousands) in urine samples after therapeutic doses. Therefore, it
has proved to be suitable also for screening of abused medicaments in psy-
chiatry. After unequivocal identification, quantification of the drugs can be
performed, if needed, preferably by GC/MS or LC/MS.

1.4.2.3 General Screening Procedures for Simultaneous
Detection of Several Classes of Acidic Drugs
in Urine after Extractive Methylation
A comprehensive GC/MS screening procedure for the detection of acidic
drugs, poisons, and/or their metabolites in urine after extractive methylation
was developed. 65–69 The analytes were separated by capillary GC and identi-
fied by computerized MS in the full scan mode. As already described above,
the possible presence of acidic drugs and/or their metabolites could be indi-
cated using mass chromatography with selective ions followed by peak iden-
tification using library search. 92,94
This STA method allows the detection in urine of most of the ACE
inhibitors and AT blockers, coumarin anticoagulants of the first genera-
66
1
67
68
tion, dihyropyridine calcium channel blockers, barbiturates, diuretics, 317
65
32
antidiabetics of the sulfonylurea type (sulfonamide part), NSAIDs, and of
69
various other acidic compounds. At least the higher dosed drugs could also
32
be detected in plasma samples after extractive methylation.
1.5 Conclusions and Perspectives
In the last few years, many papers have been published concerning GC/MS
screening in body fluids for unknown drugs and their metabolites relevant
to clinical toxicology, forensic toxicology, and doping control. They either
describe procedures for confirmation of chromatographic or immunological
results or for STA. Confirmation is usually performed in the SIM mode
because only particular compounds have to be identified. GC/MS is today
the method of choice for STA in clinical and forensic toxicology as well as
in doping control. If the drug is unknown, full scan mode is the method of
choice, since comparison of the full mass spectra with reference spectra is
necessary and provides best specificity. The screening can be performed
using mass chromatography followed by library search. Besides common
92
toxicological mass spectral libraries very large mass spectra collections with
more than 200,000 entries 95,96 can also be used. Quantification in the SIM
mode provides very good precision especially using stable isotopes as internal
standards. However, they are commercially available for only a few drugs.

© 2004 by CRC Press LLC