Quantitative and Structure Analysis of Cellulose in Tobacco by ¹³C CP / MAS NMR Spectroscopy

A new method utilizing ¹³C cross-polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectra was developed for the simultaneous quantitative determination and structure analysis of tobacco cellulose from hot water or acid detergent extraction. A reference spectrum of tobacco noncellulose components was subtracted from the spectrum of each sample to obtain a subspectrum of the cellulose components. The NMR spectra in combination with spectral fitting were analyzed in detail and some parameters, such as the content of cellulose, crystallinity, allomorph composition and lateral dimensions for cellulose elementary fibrils and microfibrils were determined. The quantitative results showed that the average recovery was 94.0% with a relative standard deviation (RSD) of 4.6–4.8%. The structure results obtained by the spectral fitting for the cellulose C1-region showed that the main allomorph composition in tobacco cellulose was I_β. The cellulose crystallinity calculated by the spectral fitting in C4 -region was about 50%. The lateral dimensions for cellulose elementary fibrils and microfibrils were in the range of 3.0–6.0 nm and 6.0–13.0 nm, respectively. Therefore, this NMR method could provide important information on both amount and structure of cellulose in tobacco.