Ion-pair chromatography of inositol polyphosphates with N-methylimipramine.

A novel counter-ion, N-methylimipramine, was synthesized and utilized in the separation of inositol phosphates by ion-pair chromatography. The structural identity of the counter-ion was documented by nuclear magnetic resonance spectroscopy. This counter-ion was capable of resolving inositol phosphates isocratically by reversed-phase high-performance liquid chromatography. Solvent polarity and ionic strength markedly affected the retention of the polyphosphorylated inositides. pH, however, was less significant in its effects. Injection of inositol trisphosphate paired to N-methylimipramine into a mobile phase containing tetrabutylammonium ions demonstrated free exchange of the inositide between the counter-ions. This counter-ion may therefore prove useful in defining empirically the mechanisms of ion-pair chromatography.