Lignin Analysis of Cotton Fiber Varieties

Five cotton bolls were randomly selected from each replicate samples of the cultivated G. arboreum A₂-100 and G. hirsutum TM-1 as well as wild G. raimondii D₅-31. Two replicated samples of the dried cotton fibers of G. raimondii D₅-31, G. arboreum A₂-100, and G. hirsutum TM-1 were cut in a Wiley mill into 20 mesh. Average contents of each cotton variety were obtained by measuring the randomly selected cotton bolls from two biological replicates. Lignin analysis was performed with pyrolysis molecular beam mass spectroscopy (pr-MBMS) by Complex Carbohydrate Research Center (CCRC) at University of Georgia. Duplicated cotton samples along with control samples including NIST 8492 (lignin content, 26.2%) and aspen standards were pyrolyzed at 500°C and the volatile compounds were analyzed for lignin using a molecular beam mass spectrometer (Extrel Core Mass Spectrometers). The raw data were processed through UnscramblerX 10.1 software to obtain the principal components and raw lignin data. G. arboreum A₂-100 fibers exclusively composed of cellulose (95.6~100%) with the lowest lignin level among cotton species was also used as the lignin base line for all tested cotton samples.