[FTIR studies of masson pine wood decayed by brown-rot fungi].

Fourier transform infrared (FTIR) spectroscopy was used to study the chemical changes of masson pine (pinus massoniana lamb.) decayed by the brown-rot fungus Wolfiporia cocos (Schwein.) Ryvarden & Gilbn. for different durations up to 23 weeks. The ratios of height of the lignin/holocellulose and holocellulose/lignin IR peaks were measured, and the klason lignin content and holocellulose content of the sound wood and brown-rotted wood with different level of decay were analyzed by wet chemical methods. The relationship between the two chemical components and the ratios of IR peak height was also established. FTIR spectra showed that, during the first 15 weeks of decay, the intensity of absorption bands at 1 736 and 1 372 cm(-1) ascribed to holocellulose decreased gradually, accompanied by a successive increase in the intensity of band at 1 510 and 1 225 cm(-1) ascribed to lignin. However, the intensities of holocellulose bands at 1736 and 1372 cm(-1) had a little increase, and the intensities of lignin bands at 1 510 and 1 225 cm(-1) had a very slight decrease after 15 weeks of decay. There was a very good correlation between the ratios of height of the lignin/holocellulose (I1510/1736, I1510/I1372, I1225/I736 and I1225/I1372) and the klason lignin content or holocellulose content. The coefficients of determination for the klason lignin content and the holocellulose content were 0.97-0.99 and 0.96-0.97, respectively. High coeffieients of determination were also obtained between the holocellulose/ lignin peak height ratios and the holocellulose content (R2 = 0.96). The above results suggest that, in the system studied, the klason lignin content and holocellulose content of wood decayed to differnent levels could be determined with reasonable accuracy by the FTIR technology.

[Determination of holocellulose and lignin content in Chinese fir by near infrared spectroscopy].

The contents of holocellulose and lignin of wood are important determinants of the pulping quality of wood. The determination of holocellulose and lignin contents using traditional chemical methods is a costly and time-consuming process. Near infrared reflectance (NIR) analysis offers a fast, nondestructive testing and low cost alternative for prediction of wood quality. In the present article, the total amounts of holocellulose and lignin contents of 48 samples were analyzed according to standard wet-chemical method. All samples were milled using a Standard Wiley knife mill with a 2 mm screen. The 2 mm material was sieved with a 40-60 mesh sieve. Then, near infrared (NIR) spectra were collected in diffuse reflectance from samples of meal contained in a spinning cup by an analytical spectral devices (ASD) Lab Spec at wavelengths between 350 nm and 2 500 nm. The raw spectra were pretreated by the second derivative and smoothing, then the NIR model was built using partial least-squares statistical analysis and full cross validation. The coefficients of correlation (r) of calibration and validation for holocellulose were 0. 96 and 0.93, respectively; the standard error of calibration (SEC) and the standard error of prediction (SEP) were 0.39 and 0.50, respectively. For lignin, the values for r of calibration and validation were 0.99 and 0.90, while the SEC and SEP were 0.10 and 0.28, respectively. It was concluded that NIR analysis is a reliable, fast and nondestructive testing predictor of holocellulose and lignin content of wood in Chinese fir.

[Rapid determination of Klason lignin content in bamboo by NIR].

Lignin is one of the main components of lignocellulosic materials. The main purpose of wood cooking and bleaching is to remove lignin by chemical agent in paper industry. Whereas the lignin content shows wide variations depending on its tree specie, site condition, part and so on, it is essential to analyze the lignin content of different raw material. The aim of this paper is to develop a rapid near infrared (NIR) reflectance spectroscopic method to characterize the Klason lignin content of bamboo. Fifty four samples from three growth years, two positions along the longitudinal directions and three positions along the radial directions within a bamboo pole were prepared. The Klason lignin contents of 54 samples were analyzed according to traditional chemical method, the spectra of these samples were collected by NIR in the range of 350 to 2500 nm, and the relationship between the lignin content and the spectra of these samples was established by multivariate statistical technique. After second derivative pretreatment of raw spectra, the Klason lignin contents of the bamboo samples were quantified using partial least-squares statistical analysis (PLS1) and full cross validation in the range of 1011-1675 nm and 1930-2488 nm. High coefficients of correlation (r) were obtained between the predicted NIR results and those obtained from traditional chemical method. The correlation coefficient of calibration model and prediction model was 0.99 and 0.97, respectively. The standard error of calibration (SEC) and standard error of prediction (SEP) was 0.36% and 0.59%, respectively. It was found that the lignin content in bamboo could be determined rapidly with reasonable accuracy by the NIR method.