Determination of iota-carrageenan with 2-thiobarbituric acid

Abstract

A colorimetric method for the determination of iota-carrageenan is described, based on the measurement of the yellow colour developed by the reaction of the 3,6-anhydro-D-galactose residue with 2-thiobarbituric acid and hydrochloric acid. The method has a sensitivity equivalent to 0·01 mg ml^–1 of carrageenan and can also be used to determine carrageenan in blood and urine in concentrations of 0·02 and 0·01 mg ml^–1, respectively. The method has advantages of sensitivity, relative specificity, a small sample-volume requirement and convenience over previously published methods for the determination of sulphated polysaccharides, thus providing a means of extending quantitative biological investigations of this group of substances.