SPECIATION OF METAL-COMPLEXES WITH BIOMOLECULES BY REVERSED-PHASE HPLC WITH ION-SPRAY AND INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRIC DETECTION

Complementarity of ion-spray MS and ICP-MS as detection techniques in reversed-phase HPLC for the characterization of metals complexed by bi omacromolecules is discussed by the example of the speciation of metal lothionein-bound cadmium. The commercially purified rabbit liver MT-2 isoform is eluted from a microbore Cg column with a gradient of up to 50% methanol in acetate buffer (pH 6.0) to give one major and three mi nor peaks detected at 254 nm. The preparation is further characterized by using an ICP mass spectrometer interfaced with HPLC via a direct i njection nebulizer which allows for the specific detection of cadmium down ro the 10 ng mL(-1) level. On-line detection by mass spectrometry with an ion-spray (pneumatically-assisted electrospray) ion source fu rther allows the determination of the molecular masses of the eluted c ompounds.