Industrial Crops and Products 11 2000 187 – 196
Multivariate chemometric analysis of the fluorescence spectra of eucalyptus wood
Evaggeli Billa
a,
, Adamantia Pastou
a
, Bernard Monties
b
, Javier Romero
c
, Emmanuel G. Koukios
a
a
Bioresource Technology Unit, Department of Chemical Engineering, National Technical Uni6ersity of Athens, Zografou Campus, GR-
15700
, Athens, Greece
b
Laboratoire de Chimie Biologique, Institut National de la Recherche Agronomique INRA
,
78850
, Thi6er6al-Grignon, France
c
Empresa Nacional de Cellulosa S.A. ENCE
,
36157
, Ponte6edra, Spain Accepted 8 October 1999
Abstract
In this paper, multivariate chemometric analysis of fluorescence spectra of juvenile and mature eucalyptus wood samples is used in order to investigate the existence of any correlation between fluorescence data and, the
physicalchemical properties, as well as the pulping data of eucalyptus wood. The results obtained demonstrated that the wood of juvenile and adult trees could be discriminated by fluorescence spectroscopy. Data analysis also has
shown the existence of good statistical correlation between fluorescence data on the one hand, and ash content, sodium hydroxide solubility, and lignin monomeric composition of the wood samples on the other hand. Moreover,
fluorescence spectral data were found to be well correlated with the pulping yield and the Kappa number of the kraft pulps issued from the adult and juvenile eucalyptus wood. © 2000 Elsevier Science B.V. All rights reserved.
Keywords
:
Chemometric analysis; Eucalyptus wood; Adult trees www.elsevier.comlocateindcrop
1. Introduction
The use of fluorescence spectroscopy as an ana- lytical method offers several inherent advantages,
including high sensitivity, specificity, rapidity, and low cost; these combined with its non-destructive
character, make it a very attractive analytical approach for various chemical and biochemical
applications Jensen et al., 1982; Bro et al., 1997. Although lignocellulosics do exhibit autofluores-
cence, fluorescence spectroscopy has not so far been an established method in this field. This is
mainly due to the structural heterogeneity and chemical complexity of lignocellulosics, contain-
ing many fluorophores that make the interpreta- tion of fluorescence data equivocal Olmstad and
Gray, 1993; Castellan et al., 1994. In particular, the classic approach consisting of finding a pair of
excitation-emission wavelengths, where the ana-
Corresponding author. Tel.: + 30-1-7723287; fax: + 30-1- 7723163.
E-mail address
:
billachemeng.ntua.gr E. Billa 0926-669000 - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 6 - 6 6 9 0 9 9 0 0 0 6 2 - X
lyte of interest is the only component giving rise to the recorded signal, is not appropriate for the
study of lignocellulosics Guilbault, 1990. More- over, although the use of fluorescence seems to
hold distinct advantages for process analysis and optimisation, is not widespread in this partic-
ular field Reibe and Eustace, 1990; Beebe et al., 1993.
Furthermore, chemometrics, i.e. the application of mathematical and statistical methods in order
to extract reliable and relevant information from chemical data, can be applied towards arriving at
tangible information from complex analytical data Miller, 1995. Until now, chemometrics-
based methods have not been largely applied in the field of lignocellulosics. We can e.g. mention
the work of Shimleck et al. 1997, who deter- mined the kraft pulp yield and carbohydrate con-
tent of wood using NIR in conjuction with a PLS technique.
Principal Component
Analysis PCA of
13C
C-CPMAS-NMR-spectra has also been employed for the estimation of cellulose I
and II in cellulosic samples Lennholm and Iversen, 1995.
In this paper, multivariate chemometric analy- sis of fluorescence spectra of juvenile and mature
eucalyptus wood is used in order to investigate the existence of any statistically adequate correlation
between fluorescence data, and the physicalchem- ical properties, as well as the pulping data of
mature and juvenile eucalyptus wood samples.
It is known that the stage of the plant develop- ment influences its physicalchemical properties,
which then play a decisive role on their pulping characteristics and the other technical properties
of the pulp and paper produced. Consequently, the age of wood harvesting is an important factor
for defining paper pulp quality. This information could be of great interest, among other things, for
the selection of criteria for the improvement of wood species.
2. Materials and methods
