title: Comparative evaluation of three lignin isolation protocols for various wood species.
abstract: Milled wood lignin (MWL), cellulolytic enzyme lignin (CEL), and enzymatic mild acidolysis lignin (EMAL) were isolated from different wood species and characterized by various techniques. The EMAL protocol offered gravimetric lignin yields 2-5 times greater than those of the corresponding MWL and CEL. The purities of the EMALs were 3.75-10.6% higher than those of their corresponding CELs, depending upon the wood species from which they were isolated. Molecular weight analyses showed that the EMAL protocol isolates lignin fractions that are not accessed by the other procedures evaluated, while 31P NMR spectroscopy revealed that MWL is more condensed and bears more phenolic hydroxyl groups than EMAL and CEL. The yields and purities of EMAL, MWL, and CEL from hardwood were greater than those obtained for the examined softwoods. Structural details obtained by DFRC (derivatization followed by reductive cleavage)/31P NMR revealed different contents of condensed and uncondensed beta-O-aryl ether structures, dibenzodioxocins, and condensed and uncondensed phenolic hydroxyl and carboxylic acid groups within lignins isolated from different wood species.
authors.affiliation: Organic Chemistry of Wood Components Laboratory, Department of Forest Biomaterials Science & Engineering, North Carolina State University, Raleigh, North Carolina 27695-8005, USA.
authors.forename: Anderson
authors.initials: A
authors.lastname: Guerra
authors.forename: Ilari
authors.initials: I
authors.lastname: Filpponen
authors.forename: Lucian A
authors.initials: LA
authors.lastname: Lucia
authors.forename: Dimitris S
authors.initials: DS
authors.lastname: Argyropoulos
mesh_terms: D028202:Abies / Q000737:chemistry; D005052:Eucalyptus / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008031:Lignin / Q000737:chemistry / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D028223:Pinus / Q000737:chemistry; D028224:Pseudotsuga / Q000737:chemistry; D032487:Sequoia / Q000737:chemistry; D013045:Species Specificity; D014934:Wood / Q000737:chemistry*
chemical_list: D008031:Lignin