CATALYTIC-OXIDATION OF TRIPHENYL PHOSPHITE WITH FERRIC ION-MODIFIED CHROMATOGRAPHIC SILICA

Triphenyl phosphite oxidation to triphenyl phosphate has been found to be catalyzed by ferric ion-modified silica stationary phases in liquid chromatographic columns. The oxidation chemistry found in this study indicates that special precautions are needed for aromatic phosphite analyses where columns may contain metals leached from stainless steel equipment. The catalytic activity can be suppressed by inert gas purging of the mobile phase to reduce its oxygen content and treating the column with a reductant to deactivate stationary phase oxidative sites. The activity can be restored by treating the deactivated column with appropriate oxidants. The on-column triphenyl phosphite oxidation reaction also can be used as a diagnostic tool to provide evidence on column contaminations with immobilized active metals and their location within the column. Using the ideal liquid chromatographic reactor model with an inert standard method, kinetic parameters for the on-column triphenyl phosphite oxidation reaction can be evaluated.