ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of carboxyl groups in the starch oxidized by nitrogen dioxide

K. Tihlárik and K. Babor

Institute of Chemistry, Centre of Chemical Research, Slovak Academy of Sciences, CS-842 38 Bratislava

Abstract:  In the studies on starches oxidized by nitrogen dioxide, a comparison of some methods of carboxyl group determination was made with low- and middle-oxidized samples. Iodometric estimation was found to be a suitable method. In a direct alkalimetric estimation, the consumption of titrating agent is not adequate and difficult to reproduce, because of the presence of lactones and other alkali labile functional groups formed in the side reactions of oxidative sample preparation. Lactones can be cleaved in the products by prolonged standing in water at room temperature or by short heating in water. Direct alkalimetric estimation affords then results comparable with other methods, but the carboxyl groups lactonize relatively quickly again.

Full paper in Portable Document Format: 375a677.pdf

Chemical Papers 37 (5) 677–684 (1983)