Approach by Raman and infrared spectroscopy in three vegetable oils from the Brazilian Amazon

Abstract

Copaiba oils (COP), Andiroba (AND) and Brazil nuts (CDB) have been studied in several areas of science, mainly due to the interest from the pharmacological and food industries. A rapid analysis by techniques such as Raman and Fourier Transform Infrared spectroscopy (FTIR) gives us information concerning thier molecular nature. Results of FTIR and Raman for COP, AND and CDB, show modes of vibrations linked to fatty acids (AFs) in the sample composition, whose structures are rich in C=O, C=C and C-H. The results suggest modes in the 800-2000 cm-1 and 2500-3000 cm-1 regions, which fit the general characteristics of the AFs, strongly associated with oleic, linoleic, and palmitic acids. COP presents a mode with an intense peak at 2800-3000 cm-1, just related to the copalic acid, that presents contributions of rings of carbon. Finally, the results were discussed with DFT calculations complementing those obtained by FTIR and Raman.