Development of Fourier transform infrared spectroscopy in direct, non-destructive, and rapid determination of cotton fiber maturity

Fourier transform infrared (FTIR) spectra of seed and lint cottons were collected to explore the potential for the discrimination of immature cottons from mature ones and also for the determination of actual cotton maturity. Spectral features of immature and mature cottons revealed large differences in the 900-1200 cm(1) region, and such spectral distinctions formed the basis on which to develop a simple three-band ratio algorithm for classification analysis. Next, an additional formula was created to assess the degree of cotton fiber maturity by converting the three-band ratios into an appropriate FTIR maturity (M(IR)) index. Furthermore, the M(IR) index was compared with parameters derived from traditional image analysis (IA) and advanced fiber information system (AFIS) measurements. Results indicated strong correlations (R(2) > 0.89) between M(IR) and M(AFIS) and between M(IR) and M(IA) among either International Cotton Calibration standards or selected cotton maturity references. On the other hand, low correlations between the pairs were observed among regular cotton fibers, which likely resulted from the heterogeneous distribution of structural, physical, and chemical characteristics in cotton fibers and subsequent different sampling specimens for individual and independent measurement.