FI-ICP-OES determination of Pb in drinking water after pre-concentration using magnetic nanoparticles coated with ionic liquid

Abstract Accurate measurement of trace metals in environmental, biological and medical samples often requires the application of enrichment and/or isolation procedures. Among the many pre-concentration and/or matrix separation techniques available, solid phase extraction procedures (SPE) are most widely employed. In the last years, surface functionalized magnetic-nanoparticles have been introduced, which offer distinct improvements compared to conventional column-based SPE approaches. In the present work, a Flow-Injection (FI) procedure for on-line separation of magnetic nanoparticles from aqueous sample solutions with subsequent ICP-OES analysis is proposed. Silica-coated magnetic cobalt nanoparticles covered with an outer layer of ionic liquid were used as sorbent material. After analyte extraction, the particle suspension was directed through an electro-magnetic trap, thereby the analyte loaded particles were separated from the sample solution. For analysis, the electro-magnet was switched off and the particles were transferred with the carrier solution to the ICP-OES used for element-specific online analysis. Compared to batch-wise methods, the FI-approach offers an additional enrichment step and requires less manual sample manipulation. Applicability of the proposed FI-ICP-OES procedure was demonstrated by the analysis of Pb in the reference material ERM-CA022a and tap-water samples collected from different districts in Vienna, Austria.