Determination of myo-inositol phosphates in food samples by flow injection-capillary zone electrophoresis

A capillary electrophoresis (CE) method with indirect photometric detection was developed to identify and quantify myo-inositol phosphates in food samples. A flow-injection (FI) system including a micro-column containing anionic exchange resin was used for the solid-phase extraction of the myo-inositol phosphates with a view to their preconcentration. The FI system was automatically coupled to CE equipment via a mechanical interface. The overall analysis time was shortened by incorporating an FI system for myo-inositol hexakisphosphate monitoring. The limit of detection for myo-inositol phosphates as determined by FI-CE ranged from 11 to 26 micromol/L and the coefficient of variation from 3.9 to 5.0%. On the other hand, the limit of detection and coefficient of variation for myo-inositol hexakisphosphate as monitored by the FI system were 75 micromol/L and 2.9%, respectively. The proposed method was successfully applied to a variety of food samples with recoveries ranging from 96.0 to 107.7% and the precision from 3.9 to 7.9%. Based on the results, the content of myo-inositol hexakisphosphate in nuts was two or three times higher than that in legumes.