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 go back to contents).
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 29-241Á, 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 Liding÷, 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 vitŠ 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, Link÷ping, 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.
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 Oxeltunet 1, SE-181 48, Sweden telephone/fax: +46 8 765 84 65|