Espectroscopia óptica: ultravioleta/visível (uv-vis) e infravermelho médio (mir) na caracterização de amostras de óleos vegetais amazônicos

Abstract

In this study, we sought to characterize copaiba (Copaifera reticulata) and andiroba (Carapa guianensis) oils through optical spectroscopy of UV-VIS and MIR absorption. The samples were acquired at Cooperativa Mista da Flona do Tapajós - COOMFLONA. The Research is of an experimental nature, carried out at the Analytical Center II, linked to the Supplementary Body Integrated Human Development Network (RIDH), located in the Technological Core Block of Bioactives (NTB) of the Universidade Federal do Oeste do Pará – UFOPA. The instruments used: UV/VIS Dual Beam Digital Spectrophotometer, Benchtop Spectrophotometer, automatically controlled through an NCL logic interface. Measurements were performed in the UV regions from 200nm to the Visible region, approximately 600nm; The mid-infrared spectra were acquired on a Fourier transform infrared spectrophotometer from a universal attenuated total reflectance accessory (UATR-FTIR), in the range of 4000 to 650 cm-1, with a resolution of 4 cm-1 and 32 scans. The crystal used in this technique contains diamond in its superior base and zinc selenide focusing element. Room temperature control (~25°C). It was possible to verify through the optical spectroscopy of absorption in the UV-VIS and spectroscopy of Medium Infrared (MIR) the properties and characterization of the vegetable oils copaiba and andiroba, of the acquired samples. The main functional groups responsible for the classification of oils were identified. The absorption bands obtained through the Middle Infrared analysis of Andiroba oil: wave number cm-1: 715-721; Vibrational mode: ẟs/τ; Functional Group: CH, and, in the same sequence, 1165-1185- ẟ- C-O; 1300-1400 - ẟ - CH3; 1465-1450 - ẟs- =CH2; 1710-1745 – ν - C=O; 2852-2850 - ẟas - =C-H2; 2924-2910 - ν - C-H3; 3005-3100 - ν - H-C=. Characteristics of the UV-VIS spectrum: absorbance of Copaiba oil, of 390 nm, at 800nm all radiation was absorbed, and for andiroba from 400 nm onwards, at 780nm all radiation was absorbed. In this way, it is possible to characterize the oils.