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Confirmation

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  347

2026-08-09

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Confirmation

Most drug exhibits must be confirmed. There are two tests that are generally recognized as confirmatory for controlled substances. It is only necessary to run one of these tests. The most common one in modern drug laboratories is GC/MS. If one has a white powder that is suspected of containing cocaine, then a small portion of the powder is dissolved in a suitable solvent such as chloroform and then filtered. The cocaine will be separated by the GC and then identified by the mass spectrometer. Many commercial GC/MS instruments have computer-based libraries of mass spectra of illicit drugs that can be compared to the spectrum of the drug exhibit. The retention time of the drug peak and its mass spectrum may give an absolute identification of the drug. The other confirmatory test for drugs is infrared spectro photometry (usually FTIR). An infrared spectrum is unique to each individual chemi cal compound (except certain isomers and homologs). Infrared spectrophotometers often come with computerized, searchable spectral libraries that aid in identification of the spectrum. One drawback to FTIR relative to GC/MS is that the drug must be separated from the cutting agents prior to obtaining the IR spectrum. In the case of small or dilute samples, this can pose a problem. Some analytical chemists who are familiar with the operation and interpretation of nuclear magnetic resonance spectroscopy use this technique for the identification of certain drugs.