Investigation of ostrich oil via Raman and infrared spectroscopy and predictions using the DFT method

Abstract

Ostrich oil (OA) containing omega-3, 6, 9, was used to obtain vibrational signatures via Raman and Fourier transform infrared spectroscopy, comparing the results generated by ab initio calculations, following a qualitative transversal approach. The density functional theory (DFT) model, whose molecular geometries were based on the B3LYP functions with the 6-311G basis set, performed by GAUSSIAN 09 packages, was chosen due it is widely used for calculations involving organic compounds. The symmetries, vibrational assignments and calculations of the potential energy distribution (PED) were done using vibrational energy distribution analysis (VEDA) software. A bibliographical approach, based on typical samples, such as oleic, palmitic, linoleic, palmitoleic, stearic and linolenic acids (fatty acids), was submitted to the theoretical stage. The results, experimental (FTIR/Raman) and calculated spectra (CS) showed modes in the regions between 1400 and 1800 cm−1, directly related to C=O and C=C belonging to carbon chains and in the range 3300–3500 cm−1, related to the OH stretching modes. The modes showed a good approximation of the composition of the material, for both FTIR/Raman and CS, therefore justifying to the use of the methodology to certify the vibrational signature of the sample.