[Fourier transformation infrared spectrometry--a new (old) method of detection in forensic chemistry and criminal investigation].
The Fourier-Transform-Infrared spectrometry (FTIR) is a very valuable technique for identifying organic substances. FTIR is more versatile in comparison to disperse infrared spectrometry, as it combines speed and sensitivity. FTIR is even superior to GC/MS: 1. Easy differentiation between isomers is possible. 2. Functional group information can be achieved instead of mass fragments. 3. GC fractions can be saved for further analysis. The FTIR instrument has no prisma or grating. It is equipped with a Michelson interferometer, which gives much more beam energy on the examination object. Most beneficial is the use of a broadband beam source, which impinges simultaneously all frequencies on the sample and on the detector. All these qualities allow the registration of fast chemical and biological processes or the observation of all reactions by volatizing and evaporation at high temperatures. IR spectrometer can run high quality infrared spectra in short time (almost 100/second) with high sensitivity. This is the basic requirement for the "on line" coupling of the IR-system with a GC. The GC peaks are analysed by IR beams with the help of a "light pipe". It is possible to examine all kinds of substances with diffuse and attenuated total reflectance methods. In special cases the change for binding of proteins and kinetic and structural processes in the flowing blood can be measured in vivo. Another use of FTIR-techniques is possible in combination with a microscope. Samples with a square aera of 8 microns can be examined. In criminalistics and forensic toxicology little particles as hairs, fibers, foams, adherents of powder in clothes, splinters of lacquer and paints etc. can be detected and identified by transmission or reflection. In conclusion, the FTIR spectrometry offers a versatility to some measurement problems that is often superior, faster and easier than other techniques such as NMR and MS.
Arnold
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D005554:Forensic Medicine / Q000295:instrumentation; D005583:Fourier Analysis; D006801:Humans; D008838:Microcomputers; D008853:Microscopy / Q000295:instrumentation; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013055:Spectrophotometry, Infrared / Q000295:instrumentation*
Die Fourier-Transformations-Infrarot-Spektrometrie--ein neues (altes) Nachweisverfahren in der forensischen Chemie und Kriminalistik.