Extraction and Isolation of Lignin for Utilization as a Standard to Determine Lignin Concentration Using the Acetyl Bromide Spectrophotometric Method (original) (raw)
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Journal of Agricultural and Food Chemistry, 2004
Present analytical methods to quantify lignin in herbaceous plants are not totally satisfactory. A spectrophotometric method, acetyl bromide soluble lignin (ABSL), has been employed to determine lignin concentration in a range of plant materials. In this work, lignin extracted with acidic dioxane was used to develop standard curves and to calculate the derived linear regression equation (slope equals absorptivity value or extinction coefficient) for determining the lignin concentration of respective cell wall samples. This procedure yielded lignin values that were different from those obtained with Klason lignin, acid detergent acid insoluble lignin, or permanganate lignin procedures. Correlations with in vitro dry matter or cell wall digestibility of samples were highest with data from the spectrophotometric technique. The ABSL method employing as standard lignin extracted with acidic dioxane has the potential to be employed as an analytical method to determine lignin concentration in a range of forage materials. It may be useful in developing a quick and easy method to predict in vitro digestibility on the basis of the total lignin content of a sample.
Journal of Animal Science, 2000
Lignin concentration can be measured in plants by the acetyl bromide-soluble lignin spectrophotometric method; however, as with any spectrophotometric method, a reliable standard is needed. In the present experiments, lignin was extracted from each of the forages under study with the acetyl bromide reagent. The lignin isolated with acetyl bromide (LIAB) was then used as the reference standard in the acetyl bromide-soluble lignin (ABSL) analysis, which was compared with the acid detergent lignin (ADL) and potassium permanganate lignin (PerL) lignin analyses. Two maturity stages of each of the following forages
Analysis of Lignin Using Qualitative and Quantitative Methods
2020
Lignin, the second richest biopolymer on earth, after cellulose and the primary deposition on the secondary cell wall structure of plants is composed of complex phenolic compounds. Its composition makes it an important natural renewable raw material for production of a number of commodity products. Lignin is also commercially produced as kraft lignin during paper manufacturing. Naturally occurring lignin plays significant biological role affecting plant growth, development, stress tolerance and adaptation. Keeping in view their commercial significance and biological role, much research has been directed towards determining the biosynthetic pathways of lignin and its qualitative and quantitative analysis. The present chapter discusses the structural features of lignin, the associated condensation and biosynthetic steps for lignin accumulation in plants, its biological functions and commercial significance. Additionally, the qualitative analysis techniques such as staining and microsc...
ANALYTICAL METHODS FOR LIGNIN CHARACTERIZATION.
Lignin characterisation is a very difficult task, if considering its diversity with respect to both origin and method of separation. The heterogeneity of lignin is caused by variations in polymer composition, size, crosslinking, functional groups, and linkage type between the phenyl propane monomers (p–hydroxy phenyl, guaiacyl and syringyl units). The elaboration of well-defined analytical methods for lignin characterization is very important for its industrial applications as a raw material. Two groups of lignin from woody species and annual fiber crops have been studied by FT-IR, UV, fluorescence and 13C NMR spectroscopy. The relative content of the different functional groups (p–hydroxy phenyl, guaiacyl and syringyl units) was appreciated by normalised intensities and deconvolution of the spectral bands. Correlation of the results provided by these methods allows the differentiation between the structural characteristics of the two lignin groups.
Analytical methods for lignin characterization. II. Spectroscopic studies
Cellulose chemistry and technology, 2006
Lignin' characterisation is a very difficult task, if considering its diversity with respect to both origin and method of separation. The heterogeneity of lignin is caused by variations in polymer's composition, size, crosslinking, functional groups, and linkage type between the phenyl propane monomers (p -hydroxyl phenyl, guaiacyl and syringyl units). The elaboration of well-defined analytical methods for lignin characterization is very important for its industrial applications as a raw material. Two groups of lignin from woody species and annual fibre crops have been studied by FT-IR, UV, fluorescence and 13 C NMR spectroscopy. The relative content of the different functional groups (p -hydroxy phenyl, guaiacyl and syringyl units) was appreciated by normalised intensities and deconvolution of the spectral bands. Correlation of the results provided by these methods permits differentiation between the structural characteristics of two lignin groups from the viewpoint of their particularities.
An overview: Importance of lignin and different analytical approaches to de-lignify it from plants
GSC Advanced Research and Reviews, 2021
In this short review, it is going to discuss the chemical structure of lignin. Hence the chemical structure of lignin is phenolic high crossed linking polymer so this type of polymers has high rigidity and not so easy to decay. Thus Lignin is insoluble in most organic solvent and water but slightly soluble in basic solutions. Mono-lignols are monomers to form crosslink polymer (lignin) and there are three main types (paracoumaryl. coniferyl and sinapyl) of these monomers. Lignin’s separation process is called delignification which is the procedure of extraction lignin from botanical source. Several analytical methods have been reviewed of delignification process and the most two common approaches are kraft pulping process by utilizing alkaline solution and organosolv pulping process by utilizing organic solvents.
Characterization and analysis of the molecular weight of lignin for biorefi ning studies
Biofuels Bioproducts Biorefining, 2014
The molecular weight of lignin is a fundamental property that infl uences the recalcitrance of biomass and the valorization of lignin. The determination of the molecular weight of lignin in native biomass is dependent on the bioresources used and the isolation and purifi cation procedures employed. The three most commonly employed isolation methods are milled wood lignin (MWL), cellulolytic enzyme lignin (CEL), and enzymatic mild acidolysis lignin (EMAL). Common characterization techniques for determining the molecular weight of lignin will be addressed, with an emphasis on gel permeation chromatography (GPC). This review also examines the mechanisms behind several biological, physical, and chemical pre-treatments and their impact on the molecular weight of lignin. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (D) all vary in magnitude depending on the biomass source, pre-treatment conditions, and isolation method. Additionally, there is a growing body of literature that supports changes in the molecular weight of lignin in response to genetic modifications in the lignin biosynthetic pathways. This review summarizes different procedures for obtaining the molecular weight of lignin that have been used in recent years and highlight future opportunities for applications of lignin
The effect of isolation method on the chemical structure of residual lignin
Wood Science and Technology, 2003
Two methods are used for the isolation of residual lignin: acidolytic and enzymatic hydrolysis. Recently a two-step procedure that is a combination of enzymatic and acidic hydrolyses was proposed. In this paper, the structures of residual lignins isolated by these three methods are compared. Enzymatic hydrolysis gave lignin with the highest yield (83%); however, it contained high amounts of carbohydrates and protein. The molar mass of enzymatic lignin was the highest, indicating that no cleavage of lignin occurred. Acidolysis gave a significantly lower lignin yield (40%), but this lignin was practically free from impurities. The b-aryl ether and lignin-carbohydrate linkages cleaved during the isolation, which was manifested in the decreased molar mass of the lignin as well as in increased phenolic hydroxyl group content. The new two-step isolation procedure gave properties between the preparations of enzymatic and acidolytic hydrolyses. The lignin yield was high (78%), but it contained some impurities, although less than the enzymatic lignin. The lignin-carbohydrate linkages cleaved to some extent, but the b-aryl ether linkages remained intact.
Lignin is the most abundant natural source of renewable aromatic units and therefore, detail characteri-sation to unveil its chemical properties is a critical step for its utilisation. Nine black liquor samples from different plant origins namely sugarcane bagasse, Eucalyptus grandis, and Pinus gregii extracted from the Kraft, soda, soda-anthraquinone and sulphite pulping processes were considered. After lignin purification, when applicable, the samples were characterised by several common methods (wet chemical methods, Fourier Transformed Infra-Red spectroscopy, Gel Permeation Chromatography). Lignin monomer composition (H:G:S) was determined by thioacidolysis as well as a new pyrolysis method based on the use of an analytical setup which couples Thermo Gravimetric Analysis (TGA) for lignin devolatilisation, the capture of released volatile compounds in thermal desorption (TD) tubes, and the quantification of the captured phenols by TD-GC–MS (gas chromatography–mass spectroscopy). The TGA-TD-GC–MS, with the use of internal calibration, allowed the quantification of 5.5–12.9 wt.% of monomeric products based on dry weight of purified lignin. Pyrolysis of sugarcane lignin resulted in significant yield of furfural, which was explained by the conversion of residual sugar. Pyrolysis of pine lignin gave the lowest yield of syringyl-type phenols, which was consistent with characterisation results (low methoxy content and absence of FT-IR band characteristic of syringyl unit). Pyrolysis method had the advantage to break different types of chemical bonds, which is likely to give a product distribution more representative of the lignin. With TGA-TD-GC–MS the monomer proportion for purified lignin from the same plant species were found to be very comparable (deviation lower than 10% for each unit). Compared to thioacidolysis (known to be selective towards bond cleavage and suspected to overestimate S content), TGA-TD-GC–MS gave lower S/G ratio. The TGA-TD-GC–MS method has demonstrated to be a good alternative technique to study the H:G:S proportions of lignins with low ash content (<5%).
Comparative study of some analytical methods to quantify lignin concentration in tropical grasses
Asian-Australasian journal of animal sciences, 2018
Lignin plays a relevant role in the inhibition of cell wall (CW) structural carbohydrate degradation. Thus, obtaining accurate estimates of the lignin content in tropical plants is important in order to properly characterize the mechanism of lignin action on cell wall degradation. Comparing conflicting results between the different methods available for commercial use will bring insight on the subject. This way, providing data to better understand the relationship between lignin concentration and implications with tropical forage degradation. Five grass species, Brachiaria brizantha cv Marandú, Brachiaria brizantha cv Xaraés (MG-5), Panicum maximum cv Mombaça, Pennisetum purpureum cv Cameroon and Pennisetum purpureum cv Napier, were harvested at five maturity stages. Acid detergent lignin (ADL), Klason lignin (KL), acetyl bromide lignin (ABL) and permanganate lignin (PerL) were measured on all species. Lignin concentration was correlated with in vitro degradability. Highly significa...