Acetyl bromide lignin contents

The acetyl bromide procedure was developed by Johnson et al. (1961) to determine lignin content in small samples from woody species. This method uses acetyl bromide (4.10) to acetylate unbound hydroxyl groups in the lignin (4.11), while the hydroxyl group on the a-carbon is substituted with a bromine group. The substituted lignin derivative (4.12) is soluble under acidic conditions, and its concentration can be measured with a spectrophotometer at 280 nm. 

Of the above methods, the acetyl bromide method appears to have earned the most widespread acceptance. This recognition can be credited to the following advantages of the procedure it is rapid and simple, adaptable to small (milligram size) samples, does not require a correction for acid-soluble lignin, provides precise absorbance values from which the lignin content can be calculated, involves minimal chemical modification of the sample, and is accompanied by diminished interference from nonlignin products. 

Measured in acetyl bromide b Measured in cadoxene c Measured in dioxane d Corrected for carbohydrates L Measured as suspension in methyl cellosolve 1 Calculation based on Klason lignin content of material 8 Variation from average, 4 5% h Absorptivity at 205 nm... 

The lignin contents of P radiata and E regnans woods and pulps determined by the standard Klason method and by the conventional and modified acetyl bromide methods are listed in Table 2 2 4 The lignin contents determined using the modified procedure generally agree better with those obtained by the Klason method than do results obtained using the conventional acetyl bromide method... 

Yield (%) based on lignin content determined by the acetyl bromide method. 

Lignin was extracted with acetyl bromide and spectrophotometrically estimated [4, 5] in control or hormone-treated segments following 40 h of incubation. U se of G A3, and better still BA + GA3, increased tissue lignin content, whereas the addition of NAA along with BA + GA3 decreased it to control or NAA-treatment levels. These results thus confirm conclusions reached by fluorescence microscopy estimates of lignification. 

Determination of Lignin Content Using Acetyl Bromide... 

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