The Quantitative Analysis of Uronic Acid Polymers by Infrared Spectroscopy

I.r. absorption bands associated with the functional groups of carboxylic acid derivatives are useful for the analysis of alginates and pectins. The ester, amide, and uronate contents of pectins and the uronate content of alginates were determined, respectively, from the ester-carbonyl stretching band (1740 cm- minus 1), the amide I band (1650 cm- minus 1), and the carboxylate antisymmetric stretching band (1607 cm- minus 1) obtained from the spectra of solutions in D2O-phosphate buffer. The results are accurate to within plus or minus 2-4%, are self consistent, and agree well with the few reliable results that are available. The method should be applicable for the determination of carboxylic acid derivatives in other polysaccharides.