The influence of column properties on metal speciation using high performance liquid chromatography-inductively coupled plasma mass spectrometry

Abstract

This paper describes an investigation into the presence of artefacts associated with the column properties on metal speciation in chromatographic systems and identifies possible limitations of columns used. The analytical procedure developed consisted of a High Performance Liquid Chromatography coupled Inductively Coupled Plasma-Mass Spectrometry system. The separation characteristics of two reversed-phase high-performance liquid chromatography columns, Hamilton C-18-PRP-1 poly-(styrene divinylbenzene) co-polymer and a conventional silica based C-18-ODS, were assessed based on the separation of metal species present at trace levels as soluble low molecular weight organic acid species. A synthetic digestive system was also employed in this study based on an enzymolysis procedure to generate dietary available metal species in the presence of fibre and multivitamins. In general, the C-18-ODS column was found to give a better separation of the organic species present compared to the C-18-PRP-1 column due to the attraction of highly polar species to uncapped silanol groups in the C-18-ODS column. The study illustrated that samples may interact with the residual silanol groups and as a result produce artefacts of chromatographic retention mechanism, peak tailing and loss chromatographic resolution.