Aplicação da espectroscopia fotoacústica na identificação das cores do algodão naturalmente colorido.

Abstract

There are two main objectives of this work. The first was to test the feasibility of using the technique of photoacoustic spectroscopy in the investigation of some physical properties of cotton fibers, a very difficult task, if not impossible in the case of fibers, by conventional UV‐visible spectroscopy. Second, seek to identify the possible types of pigments present in naturally colored cotton. The photoacoustic technique was very useful and versatile in the identification of biomolecules in flavonoids, whose spectra Photoacustic, especially in the visible range of the electromagnetic spectrum, showed that not only one but a set of molecules of the flavonoid family is responsible for the colors of cotton fibers of colored cottons. The group of flavonoids molecules observed in this work is basically formed by the following species: Gossypetin, Morin, Proanthocyanidins (condensed tannins), and VinylpyranoMv Catechin‐3‐gluc‐phloroglucinol, present in greater or lesser relative intensity observed in all species, white, brown and green. The novelty here was to verify that, besides the molecular diversity observed in the colorful species, biomolecules flavonoids are also present in white cotton, but substantially lower in intensity than in naturally colored species, in order that it escapes the field of human observation, therefore, in this case, the color white.