Application of sulphonated styrene and divinylbenzene copolymers with various degree of crosslinking for ion exclusion chromatography

The chromatographic retention of neutral polar compounds (alcohols, ketones, carboxylic acids, carbohydrates, and sweeteners) and compounds in ionized form (mono- and dibasic organic acids) on cation exchange columns filled with sulfonated poly(styrene-divinylbenzene) with a crosslinking degree of 8 % (Nautilus-IE) and 10 % (Sevko AA) is studied in a variant of ion exclusion chromatography. Using 5 mM sulfuric acid, the retention parameters of the compounds are determined and new patterns are obtained that clarify the mechanism of retention of organic acids in the ion-exclusion chromatography variant. It is found that the retention of all the studied compounds (logk’) is directly proportional to the hydrophobicity values logPexp). In this case, the electrostatic repulsion of organic acids from the sulfo groups of the cation exchanger shifts the logk’–logPexp dependences by a fixed value proportional to the number of carboxyl groups. The possibility of using the Sevko AA column not only for amino acid analysis, but also for ion exclusion chromatographic determination of organic acids and alcohols in complex samples with simultaneous spectrophotometric and refractometric detection is shown.