Ion chromatography coupled with optical emission spectrometry (IC-ICP-OES) methodology for the analysis of inositol phosphates in food and feed

This study presents the development of ion chromatography coupled with inductively coupled plasma optical emission spectrometry (IC-ICP-OES) for the simultaneous determination and quantification of inositol phosphates (InsP_x). Using a CarboPac PA100 column with a nitric acid-water gradient, 28 InsP_x isomers (InsP₆ to InsP₂) were separated within 33 min. The method eliminates baseline drift and post-column derivatization thereby simplifying detection and quantification. It achieves low detection limits of 63 μg/L P across a range of 63-3200 μg/L P. Various extraction and sample preparation methods for food and feed matrices were tested, including acidic and alkaline agents, C₁₈ SPE and spin concentrators. The analysis shows intra-day and intra-laboratory reproducibility with deviations smaller than 1 % for standard solutions and under 4 % for feed samples (80 % recovery rate of phytate). This methodology is applicable to explore enzymatic degradation pathways and the analysis of InsP_x in complex food and animal feed matrices.