Absorption spectra of cellulose

The affinity of cellulose and its derivatives for water can be explained by the existence of hydrogen bonds that bind the molecules of the cellulose chain either directly or with the help of water molecules, as outlined in Fig. 82. The existence of hydrogen bonds has been confirmed experimentally by studies of the infra-red absorption spectra of cellulose and its derivatives (the subject will be discussed later, on p. 287). 

Fig. 4.19. Ultraviolet absorption spectra of cellulose film (--------) before and ( )...

Fig. 7.2.1 Absorption spectra of Odontosyllis luciferin (solid line) and Odontosyllis oxyluciferin (dashed line), both in ethanol/water (5 6) containing 8% NaCl. To measure the latter curve, luciferin was first luminesced in the presence of luciferase, then luciferase was removed using a small column of DEAE cellulose. From Shimomura et al, 1963d, with permission from John Wiley Sons Ltd.

The absorption spectra of the fractions obtained during the purification of the PSI particles are shown in Fig la. Both the sonicate and the original 40,000 xg supernatant showed a major peak at 620 nm due to soluble phycobiliproteins, which can be completely removed by batch chromatography on DE AE-cellulose. Thus, the A620/A676 ratio, which compares the absorption maxima of blue pigments to that of chlorophyll was 2.73 in the sonicate, 3.81 in the 40,000 xg supernatant, and only 0.27 in the DE-52 eluate. 

Fig. 1. Absorption spectra of the different fractions obtained during the purification of PSI-enriched particles of P. laminosum. The spectra were recorded at room temperature on a Beekman UV 5260 spectrophotometer using 1 cm path length quartz cuvettes, (a) Sonicate (—) 40,000xg supernatant (...) DEAE-cellulose eluate (—). (b) PSI-enriched particles after chromatography on a Sephacryl S-300 column.

Figure 2. The OH stretching frequency bands in the infrared absorption spectra of bacterial cellulose (16)...

The contribution of spectroscopy to the early studies of structure was quite limited. An important contribution was made in the studies by Liang and Marchessault (24-26) wherein measurements of dichroism in infrared absorption of orTe nted specimens led to proposal of a particular hydrogen-bonding scheme. The differences between the spectra of celluloses I and II were explained in terms of differences in the packing of molecular chains and associated... 

Samples of lignin, wood, or cellulose were suspended in phosphate buffer (pH 7.0, y = 0.5) containing varying concentrations of sodium cholate, sodium deoxycholate or sodium taurocholate. The concentration remaining in the supernatant after equilibration for 20-24 h was determined by measuring the absorption spectra of polyenylic carbocations formed from bile acids in 72% sulfuric acid ( ). ... 

Figure 4. Absorption spectra of pH sensors constructed from (A) Direct Orange 8 and (B) Direct Blue 8 immobilized at hydrolyzed cellulose acetate. For (A) pH values (a) 2.0 (b) 3.0 (c) 4.0...

Hofman W, Ostrowski T, Urbanski T, Witanowski M, Infra red absorption spectra of products of carbonisation of cellulose and lignin, Chem Ind, No 45, 95, 1960. 

The separation of nucleotides and deoxynucleotides, previously a formidable task involving the fractional crystallization of heavy metal and alkaloid salts 102) has been made much easier by developments in analytical techniques. Ion-exchange methods may be used for the purification, isolation, and identification of both classes of nucleotides from hydrolysis mixtures 103), Countercurrent distribution 104) and starch 106) and cellulose-column 106) as well as paper-strip chromatography 107) have also proved to be useful in separating nucleotides from natural sources. Spectro-photometric procedures based on the characteristic ultraviolet absorption spectra of the purines and pyrimidines have been the most convenient method to locate, estimate, and identify the fractions obtained in the previous separations. Since the nucleotides are acid in nature, they are often named as acids, e.g., adenylic acid, cytidylic acid. The general constitution of the purine nucleotides (and by analogy the pyrimidine nucleotides) is demonstrated by their hydrolysis by acids to a purine and ribose (or 2-deoxyribose) monophosphate and by alkalies to the nucleosides and phosphoric acid. The order of the constituents in a purine nucleotide must, therefore, be ... 

Absorption spectra of copper(0)/cellulose and platinum(O)/cellulose normalised at 650 nm and 450 nm respectively. 

The optica] absorption spectra of lignins extend into the visible wavelength region and exhibit peaks at about 205 and 280 nm, and shoulders at 230 and 340 nm [17a]. Polysaccharides such as cellulose and amylose essentially do not absorb light at k > 200 nm. 

Fig.I (left). Absorption spectra of suspensions of/ carotene form isolated chromatographically on a DEAE cellulose column (a), or by sequential extraction (b). The absorption spectrum of a mixture of chromatographically isolated pigment and residue after extraction of lipids with J00% acetone is also shown (c).

Fig.2 (right). Absorption spectra of suspensions of crystalline/ -carotene a - before purification on a DEAE cellulose column, b - red fraction collected from the top of the column, c - red fraction passed through the column. Pigments were suspended in phosphate buffer (0.06 M, pH 7.4) containing 1% Triton X-100. 

The subject of Figs. 4-6 involves another difficult topic the examination of carbonaceous materials. In order to obtain carbons prepared under controlled conditions, the pyrolysis of cellulose was studied. Fig. 4 shows just three of many spectra of pyrolysis sequences. The numerous changes in the spectra, e.g., the decline of aliphatic C-H stretching absorptions just... 

Infrared Examination of the Residues. Cellulose Triacetate Film. ATR infrared spectra of the films irradiated at 313 mfx both in vacuum and in the presence of oxygen showed no change from those before irradiation. ATR infrared spectra of the films after irradiation at 253.7 nty, both in vacuum and in the presence of oxygen, showed additional absorptions at 5.8 and 7.85 microns, which were attributable to carboxylic acids. In some cases absorptions at 6, 10.4, 11.5, and 12.4 microns were observed, indicating the presence of unsaturation. 

Figure 2 compares ATR spectra of the irradiated and unirradiated sides of a cellulose triacetate film after 24-hour radiation at 253.7 min vacuum. The ATR spectrum of a control cellulose triacetate film, which is identical with that of the unirradiated side in Figure 2, is given in Figure 3. Figure 4 shows the change of infrared absorptions of a cellulose film cast on a NaCl plate upon irradiation at 253.7 min vaccum. The spectra were recorded at 90°C. An increase in OH (3 microns) and a decrease in carbonyl (5.7 microns) absorption were noted. 

---