Thermal discoloration fraction

Figure 1. Changes in postcolor number of filter-paper sheets with 15% add-on of hemicellulose fractions derived from various pulps. For comparison, the thermal discoloration of a test sheet of groundwood pulp, gp, is shown. The initial postcolor number represents the increase in color over that of the untreated filter paper a, daylight fluorescent lamps b, black-light fluorescent lamps c, heat (90 °C and 50% rh). Key O, blank filter paper , BP A, GP V, UBP 0, chlorited UBP.

Other antibiotics still require freeze drying, e. g. Na-Cephalotin (Na-CET). Takeda [ 1.32] showed, that thermal treatment of Na-CET was not sufficient to produce pure crystalline Na-CET, as the amorphous fraction discolors during storage and must be avoided. Takeda described the production of pure crystalline Na-CET by adding microcrystals of Na-CET to a saturated solution of Na-CET. If this mixture was frozen and freeze dried, then no amorphous or quasi-crystalline were found. Koyama et al. [3.35] described, that after thermal treatment for 24 h some parts remained incompletely crystallized. After adding 5 % (w/w) isopropylalcohol, a thermal treatment of 1 h was sufficient. Furthermore, the product could be dried at a higher pressure. Thus the drying time could be reduced and 100 % of the product could be used. 

Influence of the Hemicellulose Fraction on Thermal and Photochemical Discoloration of Paper... 

---