DESIGN AND CHARACTERIZATION OF A MICROCONCENTRIC NEBULIZER INTERFACE FOR CAPILLARY ELECTROPHORESIS-INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY

An interface for capillary electrophoresis (CE) and inductively couple d plasma mass spectrometry (ICP-MS) is reported. The interface was con structed using a commercial microconcentric nebuliser and home-built c yclonic spray chamber. Isoforms of the heavy metal binding protein, me tallothionein, were separated and the bound metals detected to charact erise the interface. Nebuliser suction was identified as the principal factor controlling separation resolution in the CE-ICP-MS system. Two methods for counterbalancing the nebuliser suction were investigated: in the first method an optimised make-up flow was employed, and in th e second a negative pressure was applied to the inlet vial. Negative p ressure was the preferred method for counterbalancing the nebuliser su ction because sensitivity was not compromised. Separation resolution, under negative pressure conditions, was improved compared with that ac hieved using on-capillary UV detection. Absolute metal detection limit s for Cd-114, Cd-111, Zn-66 and Zn-64 were 2.09, 3.42, 8.93 and 9.12 f g, respectively.