TY - JOUR
T1 - Linkage abundance and molecular weight characteristics of technical lignins by attenuated total reflection-FTIR spectroscopy combined with multivariate analysis
AU - Lancefield, Christopher S.
AU - Constant, Sandra
AU - de Peinder, Peter
AU - Bruijnincx, Pieter C.A.
N1 - The authors gratefully acknowledge the support of the Smart Mix Program of the Netherlands Ministry of Economic Affairs and the Netherlands Ministry of Education, Culture and Science.
PY - 2019/3/21
Y1 - 2019/3/21
N2 - Lignin is an attractive material for the production of renewable
chemicals, materials and energy. However, utilization is hampered by its
highly complex and variable chemical structure, which requires an
extensive suite of analytical instruments to characterize. Here, we
demonstrate that straightforward attenuated total reflection (ATR)‐FTIR
analysis combined with principle component analysis (PCA) and partial
least squares (PLS) modelling can provide remarkable insight into the
structure of technical lignins, giving quantitative results that are
comparable to standard gel‐permeation chromatography (GPC) and 2D
heteronuclear single quantum coherence (HSQC) NMR methods. First, a
calibration set of 54 different technical (fractionated) lignin samples,
covering kraft, soda and organosolv processes, were prepared and
analyzed using traditional GPC and NMR methods, as well as by readily
accessible ATR‐FTIR spectroscopy. PLS models correlating the ATR‐FTIR
spectra of the broad set of lignins with GPC and NMR measurements were
found to have excellent coefficients of determination (R2 Cal.>0.85) for molecular weight (Mn, Mw) and inter‐unit abundances (β‐O‐4,
β‐5 and β‐β), with low relative errors (6.2–14 %) as estimated from
cross‐validation results. PLS analysis of a second set of 28 samples
containing exclusively (fractionated) kraft lignins showed further
improved prediction ability, with relative errors of 3.8–13 %, and the
resulting model could predict the structural characteristics of an
independent validation set of lignins with good accuracy. The results
highlight the potential utility of this methodology for streamlining and
expediting the often complex and time consuming technical lignin
characterization process.
AB - Lignin is an attractive material for the production of renewable
chemicals, materials and energy. However, utilization is hampered by its
highly complex and variable chemical structure, which requires an
extensive suite of analytical instruments to characterize. Here, we
demonstrate that straightforward attenuated total reflection (ATR)‐FTIR
analysis combined with principle component analysis (PCA) and partial
least squares (PLS) modelling can provide remarkable insight into the
structure of technical lignins, giving quantitative results that are
comparable to standard gel‐permeation chromatography (GPC) and 2D
heteronuclear single quantum coherence (HSQC) NMR methods. First, a
calibration set of 54 different technical (fractionated) lignin samples,
covering kraft, soda and organosolv processes, were prepared and
analyzed using traditional GPC and NMR methods, as well as by readily
accessible ATR‐FTIR spectroscopy. PLS models correlating the ATR‐FTIR
spectra of the broad set of lignins with GPC and NMR measurements were
found to have excellent coefficients of determination (R2 Cal.>0.85) for molecular weight (Mn, Mw) and inter‐unit abundances (β‐O‐4,
β‐5 and β‐β), with low relative errors (6.2–14 %) as estimated from
cross‐validation results. PLS analysis of a second set of 28 samples
containing exclusively (fractionated) kraft lignins showed further
improved prediction ability, with relative errors of 3.8–13 %, and the
resulting model could predict the structural characteristics of an
independent validation set of lignins with good accuracy. The results
highlight the potential utility of this methodology for streamlining and
expediting the often complex and time consuming technical lignin
characterization process.
KW - Biomass
KW - Chemometrics
KW - FTIR spectroscopy
KW - Lignin
KW - Partial least squares modelling
U2 - 10.1002/cssc.201802809
DO - 10.1002/cssc.201802809
M3 - Article
C2 - 30641616
SN - 1864-5631
VL - 12
SP - 1139
EP - 1146
JO - CHEMSUSCHEM
JF - CHEMSUSCHEM
IS - 6
ER -