Spectrophotometric determination of carboxyl in cellulose

Abstract

Cellulose samples were dry-mixed with an equal wt. of finely divided polystyrene and then mulled with 5 ml. mineral oil per g. cellulose to form a slurry which was subjected to infrared absorption measurements. The intensity of absorption at 5.8 μ was used as a measure of the carboxyl content of the cellulose; the absorption of polystyrene at 6.2 μ was used as a reference band. The method was capable of detecting as little as 0.1 millimol. carboxyl per g. cellulose. Results agreed fairly well with chem. analysis by the Ca(OAc)2 method (cf. Yackel and Kenyon, C.A. 36, 1173.8).