关键词: 樟树, 楠木, 傅立叶红外光谱, 木素, 纤维素, 半纤维素, 二阶导数谱

Abstract: [Objective] The aim of the this paper was to establish an identification method for 2 woods(Cinnamomum camphora and Phoebe zhennan) with similar structure. [Method] Optical microscope and fourier transform infrared spectrometer(FTIR) were used in this study and anatomical structure and infrared spectroscopy characteristics were compared between the two woods. [Results] C. camphora and P. zhennan showed similar microstructure. C. camphora belonged to semi-diffuse-porous wood or diffuse-porous wood while P. zhennan belonged to diffuse-porous wood. The variation of C. camphora tangential diameter of pores was greater than that P. zhennan with average tangential diameter of(114.529 3±31.564 5) μm and(106.378 8±19.687 2) μm, respectively. According to FTIR comparison of 6 wood samples, the origin of woods have certain effects on finger-print FTIR. The infrared spectrum of two woods had a little difference in the peak shapes and peak positions, with distinction of C-O stretching vibration in cellulose and hemicellulose. The twin peaks of different peak intensity of C. camphora existed at 1 055 and 1 039 cm^-1 while the asymmetric unimodal peak of P. zhennan existed at 1 054 cm^-1. Taking the 1 510 peak as an internal standard peak, the rate of 1 595 cm^-1(C. camphora) and 1 599 cm^-1(P. zhennan) was 1.161 2 and 0.996 9, respectively, indicating that the C. camphora had a high ratio of guaiacyl group. The obvious differences in the second-derivative spectroscopy between C. camphora and P. zhennan was observed in the range of 800 cm^-1 and 1 800 cm^-1, which mainly existed in the number and shape of absorption peaks. The absorption peaks of C. camphora could be divided into 17 groups of peak cluster while P. zhennan with 17 independent absorption peaks, which only had 37.5 of matched-degree in the whole spectrum. [Conclusion] Based on the origin place, the stable FTIR between 900 and 3 400 cm^-1 was used to characterize these two woods. The absorption shape of 1 055~1 039 cm^-1 and relative intensity ratio of absorption peak of 1 595 cm^-1(C. camphora), 1 599 cm^-1(P. zhennan) and 1 510 cm^-1 may be used to characterize these two woods. The second-derivative spectroscopy could be used to identify the two woods with obvious difference.

Key words: Cinnamomum camphora, Phoebe zhennan, fourier transform infrared spectroscopy, lignin, cellulose, hemicellulose, second derivative spectra