Commercially available lignins

Typical compositions for softwood and hardwood kraft blackhquors are shown in Table 10. Most commercial kraft lignins are sulfonated kraft lignins or lignin amines. A few nonsulfonated products are, however, available. 

It has been shown that the molar mass distributions of lignin sulfonates and kraft lignin can be determined by gel permeation chromatography. Calibration of the columns with lignin sulfonates of known molar mass or, alternatively, with commercially available proteins and polypeptides has been shown to give the same result. 

Animal feeds as well as human diets vary considerably in the type and quantity of dietary fiber. Wise and Gilbert (9) using modified detergent methods analyzed fourteen commercial rodent diets and found that the total dietary fiber content varied from 8.3 to 22.4%. In fact, it is not unusual for commercially available cereal-based rodent diets to contain 20% dietary fiber on a dry weight basis (10). In general, the fermentable fibers constitute more than half of the total dietary fiber the remainder composed of the fibers more resistant to fermentation, such as cellulose and lignin (9). Thus, a significant portion of rodent diets has the potential to be fermented in the intestinal tract. 

Band fitting (curve fitting, or band shape analysis) is conveniently performed with commercially available software packages which fit, interactively or automatically, Gaussian or Lorentzian line shapes (or their combinations) to an unknown band profile. The applicability of this technique to lignin chemistry is not known at present. 

Commercially available FT NMR spectrometers (e g, Bruker, Vanan, GE, JEOL) are designated by their H operating frequency ranges (Table 5 4 1) Satisfactory nC NMR spectra of lignin can be obtained with 200 and 250 MHz spectrometers Higher field provides greater sensitivity and is used when enhanced sensitivity is a critical requirement The following instrument specifications are important... 

Essentially all of the lignin commercially available is isolated as byproducts from either the sulphite or the kraft process. Table II gives a very conservative idea of annual lignin production in the United States (2) and worldwide 36). 

This study on the bleaching chemistry of amineboranes with lignin model compounds has resulted in a bleaching efficiency ranking for those commercially available amineboranes [75]. The most efficient is tcrt-butylamineborane, closely followed by borane-ammonia. The third most efficient is dimethylamineborane, followed by the tertiary amines (trimethylamineborane and triethylamineborane). 

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