DETERMINATION OF D H RATIOS OF NONEXCHANGEABLE HYDROGEN IN CELLULOSE - A METHOD BASED ON THE CELLULOSE-WATER EXCHANGE-REACTION/

We have established a simple technique for the determination of D/H ra tios of nonexchangeable hydrogen in cellulose. This technique is based on equilibrating cellulose prepared from raw wood or cotton with wate r of known isotopic composition. A temperature of 0-degrees-C was sele cted for the exchange experiments. This allowed the rapid freezing and subsequent sublimation of the ice without affecting the isotopic comp osition of the equilibrated hydroxyl hydrogen. A sodium hydroxide trea tment of the cellulose is necessary to achieve equilibrium between cel lulose and water within 24 hours. The best sodium hydroxide treatment procedure was found to be overnight soaking of cellulose in a 17% NaOH solution at near 0-degrees-C, followed by rinsing and transferring th e cellulose to the exchange vessels without drying. We have obtained a very good reproducibility for the deltaD analysis of the equilibrated cellulose treated with this procedure (1 sigma < 2 parts per thousand ). The resulting deltaD values of nonexchangeable hydrogen, using the equilibration technique, were compared with those obtained using the n itration technique. The agreement between the two techniques is +/-3.3 part per thousand (1sigma), and the analytical accuracy of the equili bration method is +/-2.5 parts per thousand (1sigma). This method may be useful in dealing with the nitration of ancient plant materials, wh ich is sometimes not possible. In addition, the technique may be exten ded to the isotopic analysis of other organic compounds that contain e xchangeable hydrogen.