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NCJ Number: 134440 Find in a Library
Title: Identification of Drugs by Their Near Infrared Spectra
Journal: Journal of Forensic Sciences  Volume:37  Issue:1  Dated:(January 1992)  Pages:35-41
Author(s): W H Kohn; A N Jeger
Date Published: 1992
Page Count: 7
Type: Report (Technical)
Format: Article
Language: English
Country: United States of America
Annotation: The identification of chemical substances, a routine procedure in forensic laboratories, can be achieved reliably by near infrared spectroscopy.
Abstract: Fourier transform spectrometers in the near infrared region, equipped with optical fiber bundles and driven by fast computers, can measure and identify drugs in a few seconds. The advantage of the near infrared region is its lower absorptivity, which makes sample preparation unnecessary. Spectra of powders are obtained in the diffuse reflectance mode directly from the sample surface. Near infrared spectra were obtained in the current investigation within 5 seconds using a Fourier transform spectrometer that used polarized light from a halogen lamp and birefringent properties of a moving quartz wedge to generate an interferogram. Remote sensing was possible by a quartz optical fiber bundle with a probe head. A library with 37 spectra of drugs and other powders for stretching drugs, such as saccharoses, was generated. It was determined that the decomposition of a reference library into principal components has two advantages: it uses the full spectral information, and it achieves considerable data reduction. The method's reliability can be improved using the first derivative of spectra, rather than the spectra themselves. Identification can be performed even with structurally related substances. Remote measurement by a quartz optical fiber probe allows the identification to be made in any container within a few seconds and without sample preparation. A drawback of the equipment used in the current study is the need for several grams of material for analysis. 4 references, 3 tables, and 1 figure (Author abstract modified)
Main Term(s): Drug testing
Index Term(s): Forensic sciences; Infrared techniques; Spectroscopy
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