DETERMINATION OF INOSITOL PHOSPHATES IP3-IP6 IN RAPESEED AND RAPESEEDMEAL BY AN HPLC METHOD .1. METHOD

An HPLC method for the determination of phytic acid and three of its d egradation products (IP3, IP4, IP5) in rapeseed and rapeseed meal has been developed. The method is based on ion pair chromatography with an RP-8-Phase and tetrabutylammoniumhydroxide as ion pair reagent. Metha nol and twice distilled water (1:1) are used as mobile phase. The comp ounds are detected by an RI-detector. Variations in retention times an d peak areas are avoided by thermostating the detector, the solvent re servoir and the column at 40 degrees C. The calibration of the system is achieved with pure phytic acid. Different response factors for the inositol phosphates were calculated. An extraction method for inositol phosphates from rapeseed samples is optimized. The inositol phosphate s of rapeseeds are extracted with 0.5 M HCI at 100 degrees C and clean ed up by an ion-exchange column. Degradation of inositol phosphates is not observed during this treatment.