The results from analysis of volatile organic
compounds (VOCs) may have toxicology
and forensic implications. Some of the VOCs
give pharmacological effects that make them popular to ingest or inhale. A
search of body fluids from a suspected drug abuser for these substances should,
therefore, be included in the complete toxicological examination (reference 1 and 2).
VOCs may be important
arson indicators. I, thus, recently showed that VOCs
in the body remains of a fire death can yield valuable information about the start
of the event. This possibility is based on the ability of body fluids or
tissues to provide an efficient heat protection of high volatile compounds
inhaled by the victim and deposited in his body. The post-mortem material is,
thus, often the only site of a fire scene where residues of such low boiling
accelerants used to start an arson can be detected (reference 3 and 4), or quantitated (reference 5).
An over-the-counter drug formulation generally contains residues of
solvents used in the manufacturing, and these may form a
"fingerprint" of a particular drug preparation.To reveal a drug copy,
the search of pharmaceuticals for VOCs
is, thus, another forensic implication, and of possible interest for a drug
company (reference 6 or
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Great
demands must be made upon a method for analyzing VOCs,
and aiming at the type of investigations mentioned above. Since the analyst
generally does not know in advance what VOC
to focus on, he needs a sensitive screening method to detect trace amounts of
the volatile "general unknown". This type of low-molecular-weight
compounds often yield rather unspecific mass spectra, which, therefore, will
not suffice as the sole identification tool. Moreover, the quality of the test
material varies to a great extent, making the distribution of the analyte
between the gasified and the solid part of the sample unpredictable. For the
quantification the chemist must, therefore, use a technique that negates the
matrix effects of the specimen.
The apparatus
set up that I have devised for testing any sample - biological or
solid - for VOCs, and
which fulfills the above requirements, is based on:
Since
the ion-trap detector is run in the scan mode, most ions, which may be formed
during electron impact of low-mass volatiles, will be monitored. This means
that the necessary data for the analysis of the large number of these
substances are obtained in a singel laboratory experiment, and that the
remaining data exam can be done just with the computer. To reveal the VOCs
in a test sample, the evaluation
of raw data is done in three steps:
By the use of a data program, reconstructing mass chromatograms with each of
the 213 ions monitored and making up the total ion current in the mass range 29-241µ,
the volatile "general unknown" can be detected.
Identification
of a volatile "general unknown" is based on the resemblance of both a
detected peak´s retention index and its mass spectrum with corresponding
literature data.
Quantitative determination of an
identified substance is done after extraction by the full evaporation
technique. All methodological details will become
available if you consult the scientific literature listed below under "References". The
investigation of a suspected intoxication
death, drug copy, or arson will bring you
through some of the analytical steps, and also hopefully help explain the
principle of the techniques.
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The
intention of my distributing this web page is to get in contact with a
laboratory that would be interested in having the headspace gas chromatography
ion-trap method set up for unbiased search for volatiles, as well as their
identification and quantification in solid or wet samples. I am interested in
taking on a temporary laboratory position, and my contribution will be to get
the method going at your location. I also welcome taking part in collaborative
work at your laboratory on scientific problems that the technique could help
solving.
In addition to
a laboratory with basic facilities for analytical chemistry, I need access to a
headspace sampler, gas chromatograph, and ion-trap detector (old or new does
not matter, but it has to be equipped with automatic gain control). More technical details are
given below. If you are interested, contact Jan Schuberth, Oxeltunet 1, SE-181
48 Lidingö, Sweden, tel/fax: +46 (0)8 765 84 65.
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I
got a M.D. degree at Karolinska Institutet, Stockholm and Ph.D. degree in
biochemistry at the Medical Nobel Institute, Stockholm. My curriculum vitæ
shows positions at the Research Institute of National Defence, Stockholm; the
Psychiatric Research Center, Uppsala University (position paid by the Medical
Research Council); Laboratory of Preclinical Pharmacology, NIMH, Saint
Elizabeths Hospital, Washington DC; Department of Pharmacology, Brain Research
Institute, UCLA School of Medicine, Los Angeles; and the Swedish National
Forensic/toxicology Laboratory, Linköping, which I was heading as a professor
between 1979 and 1990. A number of articles published in various scientific
journals and dealing with enzymology, the acetylcholine metabolism, opiate
determination and "poppy seed defence" are on my list.
During the
last five years before reaching the status of a senior citizen in 1995, I was
working as a research professor at the Forensic/toxicology Laboratory, and
developed during this period the methods for analysing VOCs in biological and
solid samples. This work resulted in the publications listed below under "References".
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Jan Schuberth, M.D., Ph.D |