Preparative fractionation of lignin by gel‐permeation chromatography

Abstract

SynopsisThe combination of an agarose gel (Bio-Gel A) and a dioxane-water (1:l) solvent system allowed the fractionation, on a preparative scale, of a very polydisperse, nonderivatized lignin preparation (enzymatically liberated lignin prepared from sweetgum sapwood with Lenzites trabea). Three fractions differing markedly in molecular weight were obtained. A gel of crosslinked alkylated dextran (Sephadex LH-20) with the same solvent system allowed division of the lowest molecular weight fraction into two fractions. These materials were characterized by measurements of intrinsic viscosity and number-average molecular weights in dimethylformamide and dioxane-water.It was established that the two highest molecular weight fractions were associated in an average trimeric form in dioxane-water (1 :1) as compared to the form (considered to be molecular) that occurred in dimethylformamide. Molecular size distributions and eluant volumes of the fractions were determined with a Sephadex G-1Wformamide system, the latter being one of the most powerful nonaqueous solvents for lignin. Adsorption effects were known to be absent in this case, and the lignin molecules were considered to be unassociated in formamide. The four fractions were distinguishable with the f0rmamide-G-100 system, thus indicating that the original fractionation was based on molecular size. The enzymatically liberated lignin contained molecules that comprised a continuum of molecular weights from approximately monomeric to molecules that were a t the limit of the solvating power of dioxane-water (1:l) and dimethylformamide. Limited physicochemical data were consistent with a compact, approximately spherically symmetric shape of the lignin in solution.

Decomposition of Lignin by White-rot Fungi. I. Isolation of Heavily Degraded Lignins from Decayed Spruce

“…The exclusion volume of this column was determined with a high molecular weight lignin (M n = 5000) (Kirk, Brown and Cowling 1969) to be 75 ml; the peak of elution curves of small molecules (veratryl alcohol, ferulic acid, etc.) Samples (10-25 mg) of each lignin in 3 ml of formamide were applied to the top of the column aikl elution was with formamide at no-115 ml per hour; the effluent was monitored at 280 nm.…”

The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films

“…In order to solve this problem and improve lignin utilization in the materials field, several techniques have been developed to obtain homogenous lignin fractions. Historically, gel permeation chromatography [29], ultrafiltration [30,31] and selective precipitation [32,33] were applied to fractionate lignin into sub-fractions with improved homogeneity. More recently, renewed interest in fractionating lignin into homogeneous fractions using organic solvents has arisen [34,35].…”

Preparation and microbial decomposition of synthetic [14C]ligins.

“…Number average molecular weight (Ml,) was determined by vapor pressure osmometry at 370 with dimethylformamide as solvent (19) Aqueous lignin suspensions (10-100 gl) containing [10][11][12][13][14][15][16][17][18][19][20] mg/ml were added to 10 ml of scintillation fluid consisting of 10 These wood-destroying fungi were incubated with the labeled lignins in closed 125 ml erlenmeyer flasks that contained 2 g of a 1:1 mixture of ground aspen and spruce wood (20 mesh = 7.9 openings/cm), 2 ml of a filter-sterilized basal medium (below), and 3 ml of lignin suspension (640 Ig, 5 X 104 dpm). Lignins in dimethylformamide solution (20-30 mg/ml) were added aseptically to sterile distilled water to give a fine suspension; no contamination problem was encountered.…”