Semimicro determination of cellulose in biological materials.

The quantitative determination of cellulose in biological materials presents some difficult problems. The moisture con~ent of cellulose varies with the relative humidity, so that accurate analyses require that moisture determinations be made under carefully standardized conditions. Cellulose ordinarily occurs in association with lignin, polyuronide hemicelluloses, and xylan cellulosans. Matrone, Ellis, and Maynard (4), who were interested primarily in the nutrition of ruminants, pointed ou~ that the xylan cellulosans are probably digested to the same extent by animals as true cellulose, and therefore recommended a modification of the method of Norman and Jenkins (5), which determines true cellulose and xylan eellulosans together, over the method of Kiirschner and Hanak (3) or the Crampton and Maynard (1) modification of this method, in which xylan cellulosans are partially or completely removed, so that cellulose is determined alone. All of these methods are laborious gravimetrie procedures in which the sample, ground to 40 mesh or finer, is repeatedly extracted with a series of hot solvent mixtures which remove lipides, proteins, lignin, and hemicelluloses. The residue is then dried at 105 ° to 110°C, and weighed, and cellulose is determined by the weight~ loss on ignition. Our objective was to develop a simple, rapid, colorimetric method for the determination of cellulose in a large number of cultures of cellulolytic bacteria and fungi. Since the procedure of Crampton and Maynard required much less time for extractions than that of Matrone, Ellis, and Maynard, it was chosen as a starting point. The sedimentation of the cellulose, extraction with the acetic acid/nitric acid reagent of Crampton and Maynard to remove lignin, hemicellulose, and xylosans, and final solution of ~he sample in 67% tt~SQ (v/v) were all carried out in a single 15 ml centrifuge tube. Cellulose was then determined on an appropriate dilution of the sulfuric acid solution by the anthrone method of Scott and Melvin (7).