High-Performance Chromatographic Separation of Inositol Phosphate Isomers on Strong Anion Exchange Columns

Inositol phosphates are focused on because of their functions in the cell, as well as their effects on the bioavailability of certain minerals. To improve the separation of inositol hexakis- to monophosphates (InsP6−InsP1) and their positional isomers, six different strong anion exchange columns (OmniPac PAX-100, CarboPac PA-100, CarboPac PA-10, IonPac AS11, Mini Q PC 3.2/3, and ION-120 anion column) were compared in two ion chromatographic analysis systems. InsP2−InsP6 were acidic gradient eluted, postcolumn derivatized, and UV detected in system 1, and InsP3−InsP1 were alkali gradient eluted and detected using chemically suppressed conductivity detection in system 2. Differences in retention data were shown depending on the column characteristics for inositol phosphates with various numbers of phosphate groups attached to the inositol ring. In system 1 the anion exchange columns PA-10 and PA-100 were best suited for the separation of isomers of InsP2 and InsP6−InsP3, respectively. Mobile phase optimization was used to successfully separate inositol phosphate isomers, as illustrated in a food sample. In system 2, PAX-100 and AS11 were the only columns useful to separate isomers of InsP3−InsP1 and InsP3−InsP2, respectively, using the current eluent (NaOH). Keywords: Ion chromatography; anion exchange columns; inositol phosphate isomers