For molecular weight determination the fractionated samples were derivatized with benzoyl chloride in [amim]Cl solution following the procedure introduced by Zoia et al. [59] and analyzed using HP G1312A pump connected to Waters HR5E and HR1 columns with a Waters 484 UV-absorbance detector calibrated using polysty­rene standards. Acid insoluble (Klason) lignin and acid soluble lignin were deter­mined by method modeled from one published by Dence [75]. The acid that was used to hydrolyze the samples was diluted from conc. sulfuric acid corresponding to 72 ± 0.1 %. The lignocellulose samples were dried in a vacuum oven at 40 °C overnight. ca. 100 mg of the samples were measured accurately and mixed with sulfuric acid solution (100 mg per 2 mL) using magnetic stirring and vortex mixer. After 2 h hydrolysis at room temperature with occasional manual mixing the samples were diluted with 50 mL of deionized water and transferred into sealable bottles. The bottles were placed into a commercial pressure cooker and heated at elevated pressure for 90 min. The solid residues were filtered with a grade-3 sinter and washed with 40 mL of water. The filtrate was retained for acid soluble lignin determination. The solid residue was further washed with 60 mL of water, so that filtrate was neutral, and after air-drying the sample was placed into a vacuum oven for 20 h. Acid soluble lignin was determined spectrophotometrically from the retained filtrates. The filtrates were first diluted to precisely 100 mL and then the absorbance was measured at 205 nm wavelength in a 1 cm pathlength cuvette. The concentrations were calculated using extinction co-efficient of 110 L/g. cm.

FT-IR spectra were recorded from finely powdered samples that were dried for 20 h at 50 °C in a vacuum oven, using Perkin-Elmer Spectrum One AT-IR spectrometer. Processing was carried out using PE Spectrum One software. The spectra were processed with baseline correction, noise elimination and normalization.