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There are two methods for the determination of carbonyl group in cellulose by means of reduction with NaBH4. One is the gasometric method proposed by Lindberg et al., and another is the volumetric method proposed by Lyttle et al. The former involves some troubles in its analytical operation. Therefore the authors adopted the latter, and carried out some experiments in order to check up the method.An analytical method now established is as follows. After a sample containing carbonyl group, such as D-glucose or oxydized cellulose by HIO4, is immersed in 0.010.13 M NaBH4 (pH 12.012.3) for 2448 hrs at room temperature and then filtered, a 0.040.4 N KIO3 solution and a 0.5 N NaOH solution are added to the filtrate successively. The amounts of consumed NaBH4 are calculated from the amounts of consumed KIO3 estimated by a titration With a 0.1 N Na2S2O3 solution in acidic condition.At a range of pH 12.012.3, 57% of the amount of consumed NaBH4 are effective for the reduction of carbonyl group in the sample. This is confirmed by the amounts of non-reacting hydrogen gas estimated with a gas burett.The results of treatment of D-glucuronolaeton and the oxydized cellulose by NaBH4 at pH 12.012.3 show that the carboxyl group and its lacton are resistant to the reduction.

Determination of Carbonyl Group in Cellulose by Sodium Borohydride Reduction Method