An alternative interface for CE–ICP–MS cadmium speciation in metallothioneins based on volatile species generation

• Published in: Analytica chimica acta Vol. 546; no. 2; pp. 236 - 243
• Main Authors: Álvarez-Llamas, G., Fernández de la Campa, M.R., Sanz-Medel, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 08.08.2005; Elsevier
• Subjects: Analytical chemistry; Cadmium; Chemistry; Exact sciences and technology; ICP–MS; Metallothioneins; Spectrometric and optical methods; Vapour generation; Cadmium; CE; Vapour generation; ICP–MS; Metallothioneins; Peak resolution; Performance characteristic; Rabbit; Nebulization; Inductive coupling plasma spectrometry; Thioureas; Cobalt; Hydrogenation; Hydrochloric acid; Efficiency; Detection limit; Thiourea; Speciation; Flow injection; Catalytic reaction; Coupled method; Lagomorpha; Repeatability; Vertebrata; Mammalia; Linearity; ICP-MS; Mass spectrometry; Catalyst; Metallothionein
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2005.05.016

An alternative CE–ICP–MS interface based on volatile species generation (VSG) is here developed, evaluated and compared to the conventional sample introduction systems via nebulisation. For this purpose, the speciation of Cd–metallothioneins (MTs) in rabbit liver is taken as a model. Cd, bound to the different MT isoforms previously separated by CE, is transformed into volatile species at the exit of the capillary and on-line detected by ICP–MS. Optimum conditions for Cd VSG have been investigated in a flow injection device, using NaBH 4 as hydrogenation reagent in a HCl medium containing cobalt and thiourea as catalysts. Sample volume injected, CE separation voltage and reagents flows have been optimised. Analytical performance characteristics of the CE–VSG–ICP–(Q)MS coupling developed were evaluated, in terms of repeatability and linearity of response, using standard rabbit liver metallothionein isoforms (MT1 and MT2). Detection limits for Cd–MTs turned out to be almost one order of magnitude better than those derived from using a conventional Babington nebuliser-based interface. Compared to a MicroMist-based interface detection limits resulted to be similar, but the observed peak height was eight times higher using the VSG interface, indicating the enhanced analyte transport efficiency derived from VSG sample introduction systems.