Use of surface-modified capillaries in the separation and characterization of metallothionein isoforms by capillary electrophoresis inductively coupled plasma mass spectrometry.

The separation of metallothionein (ML) isoforms using capillary electrophoresis (CE) has been improved by applying surface-modified capillaries, and the metal composition of MTs has been characterized by subsequent inductively coupled plasma sector field mass spectrometry (ICPSFMS). Nine MT complexes in a commercial preparation from rabbit liver were successfully separated on an anionic polymer-coated column, prepared by immobilizing poly(2-acrylamido-2-methyl-1-propanesulfonic acid) on the fused-silica surface via a linking agent. On uncoated capillaries or those coated dynamically with cationic materials, only three complexes could be separated. Online isotope dilution analysis combined with CE/ICPSFMS indicated the stoichiometric molar metal contents in the MT complexes.