Applications of Fourier Transform Infrared Spectroscopy to Study Cotton Fibers

Abstract

Fourier Transform Infrared microscopy (FTIR) has become an essential analytical tool available to scientists to study various materials. Specifically FTIR has been increasingly used to study cell wall developments in plants, investigate the efficiency of the surface modification of polymers, identifying contaminants, and predicting the physical properties of certain polymers and biopolymers, etc. This chapter reviews some selected application of the FTIR to study cellulose development in cotton fibers and to predict cotton fiber physical properties. Cotton fiber maturity is a major yield component and an important fiber quality trait that is directly linked to the quantity of cellulose deposited during the secondary cell wall (SCW) biogenesis. Cotton fiber development consists of five major overlapping stages: differentiation, initiation, polar elongation, secondary cell wall development, and maturation. The transition period between 16 and 21 dpa (days post anthesis) is regarded to represent a major developmental stage between the primary cell wall and the SCW. Fourier Transform Infrared spectroscopy was used to investigate the structural changes that occur during the different developmental stages. The IR spectra of fibers harvested at different stages of development (10, 14, 17, 18, 19, 20, 21, 24, 27, 30, 36, 46, and 56 dpa) show the presence of vibrations located at 1,733 cm-1 (C=O stretching originating from esters or amides) and 1,534 cm-1 (NH2 deformation corresponding to proteins or amino acids). The results converge towards the conclusion that the transition phase between the primary cell wall and the secondary cell wall occurs between 17 and 18 dpa in fibers from TX19 cultivar, while this transition occurs between 21 and 24 dpa in fibers from TX55 cultivar. The Universal Attenuated Total Reflectance FTIR (UATR-FTIR) was used to evaluate the cotton fiber properties. One hundred and four cotton samples were selected. Thirty FTIR spectra were acquired from each sample and analyzed. Partial Least Square (PLS) analysis of the FTIR spectra was performed and the results showed that micronaire and surface area (calculated from the AFIS data) could be predicted from the FTIR measurements with very high coefficients of determination. However, the prediction of fiber maturity is probably not possible with the UATR-FTIR. It was concluded that, to be able to predict the fiber maturity with the FTIR, it would be necessary to perform the measurements in the transmission mode rather than in the reflectance mode.