Identification of cadmium-bioinduced ligands in rat liver using parallel HPLC-ICP-MS and HPLC-electrospray MS

Abstract

An analytical strategy has been developed for the characterization of Cd complexes in rat liver tissue. The sample preparation included the isolation of the Cd–macromolecular fraction by semi-preparative size-exclusion chromatography, followed by a preconcentration step by lyophilization and desalting. The analysis was carried out by microbore reversed-phase HPLC with parallel ICP-MS and ESMS detection. The HPLC-ICP-MS interface was based on a Micromist nebulizer and a low dead volume cyclonic spray chamber. The HPLC-ESMS interface allowed the measurement of the molecular mass of the ligand protein owing to the dissociation of the complex by the on-line post-column acidification of the eluate. The approach allowed the detection of two major metallothionein (MT)isoforms and their identification on the basis of the molecular mass as rat liver MT-1 and MT-2. The actual number of peaks in the chromatograms was larger because of the formation of mixed Cd–Cu complexes of the same MT isoform that showed different hydrophobicities.