Identification of Different Forms of Cocaine and Substances Used in Adulteration Using Near-infrared Raman Spectroscopy and Infrared Absorption Spectroscopy

Author(s)

Penido, Ciro A. F. O. ^[1] ; Pacheco, Marcos Tadeu T. ^[1] ; Zangaro, Renato A. ^[1] ; Silveira, Jr., Landulfo ^[1]

Affiliation

^[1] Univ Camilo Castelo Branco UNICASTELO, Biomed Engn Inst, BR-12247016 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF FORENSIC SCIENCES; v. 60, n. 1, p. 171-178, JAN 2015.
• Web of Science Citations: 22

Abstract

Identification of cocaine and subsequent quantification immediately after seizure are problems for the police in developing countries such as Brazil. This work proposes a comparison between the Raman and FT-IR techniques as methods to identify cocaine, the adulterants used to increase volume, and possible degradation products in samples seized by the police. Near-infrared Raman spectra (785nm excitation, 10sec exposure time) and FT-IR-ATR spectra were obtained from different samples of street cocaine and some substances commonly used as adulterants. Freebase powder, hydrochloride powder, and crack rock can be distinguished by both Raman and FT-IR spectroscopies, revealing differences in their chemical structure. Most of the samples showed characteristic peaks of degradation products such as benzoylecgonine and benzoic acid, and some presented evidence of adulteration with aluminum sulfate and sodium carbonate. Raman spectroscopy is better than FT-IR for identifying benzoic acid and inorganic adulterants in cocaine. (AU)

• FAPESP's process: 09/01788-5 - Dispersive Raman spectroscopy using optical fibers "Raman probe" applied to the diagnosis of neoplasia in the skin and prostate
• Grantee: Landulfo Silveira Junior
• Support Opportunities: Regular Research Grants