Determination acid-soluble lignin

Soluble and insoluble lignin were determined with the NREL standard biomass analytical methods for the analysis of acid-insoluble and acid-soluble lignin inbiomass, LAP-003 and LAP-004, respectively (13-14). NREL s laboratory analytical procedure for the determination of carbohydrates in biomass, LAP-002, without correction for hydrolysis losses was performed to determine the sugar content (15). 

Note 4. When the concentration of acid-soluble lignin in the filtrate is to be determined, a reflux condenser should not be used to maintain constant volume during boiling. 

Note 5. If acid-soluble lignin is to be determined, a sample of the undiluted supernatant solution or filtrate is removed. 

Determination of Acid-Soluble Lignin in Wood and Pulp... 

The acid-soluble lignin contents of wheat straw and bamboo have been reported as 2 and 1.5%, respectively (Schoning and Johansson 1965). In such cases, where an accurate value for total lignin content is required, acid-soluble lignin must be determined and the value applied as a correction to the acid-insoluble lignin content. 

Maekawa F, Ichizawa T, Koshijima T (1989) An evaluation of the acid-soluble lignin determination in analysis of lignin by the sulfuric acid method J Wood Chem Technol 9 549-567... 

Pearl IA, Busche LR (1960) Studies on the chemistry of aspenwood XI The Klason lignin determination as applied to aspenwood with special reference to acid-soluble lignin Tappi 43 961-970... 

Schoning AG, Johansson G (1965) Absorptiometric determination of acid-soluble lignin in semichemical bisulfite pulps and in some woods and plants Sven Papperstidn 68 607-613 Schultz TP, Templeteon MC, McGinnis GD (1985) Rapid determination of lignocellulose by diffuse reflectance Fourier transform infrared spectrometry Anal Chem 57 2867- 2869 Sjostrom E, Enstrom B (1966) Spectrophotometnc determination of the residual lignin in pulp after dissolution in cadoxene Sven Papperstidn 69 469-476... 

Srinivasa Rao Y, Shukla RN, Maheshwari S, Kulkarni AY, Jivendra Y (1983) Determination of permanganate and kappa number of pulp with high ash content. IPPTA 20(3) 55-56 Stewart CM, Foster OH, Cohen WE, Leslie RT, Watson AJ (1951) The selection and preparation of a reporducible wood sample for chemical studies. Appita 5 267- 311 Swan B (1965) Isolation of acid-soluble lignin from the Klason lignin determination. Sven Papperstidn 68 791-795... 

Table 4.4.1 gives the distribution of lignin in Douglas-fir (Pseudotsuga menziesii) earlywood tracheids (Saka and Thomas 1982). The overall lignin content (W) of the earlywood portion is 0.285 gig). The Klason and acid-soluble lignin determinations should be made on wood taken near the location from which the sections are collected for EDXA measurements. 

The absorbance at either 205 or 280 nm is the basis of several techniques for the quantitative determination of lignin. The extinction coefficient depends on species and solvent, and varies from 10 to about 26 L g cm. Summaries of extinction coefficients are available in reviews by Dence [18], Lin [2], and Fengel and Wegener [19]. Lin [2] has provided guidelines for measurement of lignin absorption spectra, while Dence [18] provides instructions for determination of acid-soluble lignin and lignin solubilized by the acetyl bromide method. 

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