Simultaneous determination of chemical vapour generation forming elements (As, Bi, Sb, Se, Sn, Cd, Pt, Pd, Hg) and non-chemical vapour forming elements (Cu, Cr, Mn, Zn, Co) by ICP-OES

Abstract

Silica-coated magnetic nanoparticles (MNPs) modified with [1,5-bis(2-pyridyl)-3-sulphophenyl methylene]thiocarbonohydrazide (PSTH-MNPs) were synthesized and characterized. These magnetic nanoparticles (PSTH-MNPs) were employed as a solid phase extraction (SPE) adsorbent for the separation and concentration of trace amounts of 14 elements (Pd, Cr, Mn, Zn, Cd, Hg, As, Sb, Bi, Cu, Pt, Sn, Se, Co) from environmental water samples. The main aim of this work was to develop a precise and accurate method for the simultaneous determination of the maximum possible number of elements by using this new absorbent and a multimode sample introduction system (MSIS). The MSIS acts as a system for the generation, separation and introduction of chemical vapours (CVG) and also as an introduction system for sample aerosols, in a simultaneous form, into an inductively coupled plasma-optical emission spectrometer. The on-line SPE-CVG-ICP-OES system developed was applied in the determination of the aforementioned metals in natural water samples (sea water, estuarine, lake and river water), with the least demanding and simple sample preparation procedure. The developed method was validated by analysing natural water certified reference materials (SLRS-4, TMDA 54.4, SW2 Batch 125, SRM 1643e). Sea water and well water samples collected from Malaga (Spain) were also analysed. The procedure has been demonstrated to be fast, easy, automatic, selective and economical, and the sensitivity was good. The main advantage of PSTH-MNPs is its very good stability and resistance because chemisorption of chelating molecules on the surface of solid supports provides immobility, mechanical stability and insolubility. The precision (RSD), accuracy (by standard addition or recovery) and limit of detection (LOD) were used to evaluate the characteristics of the procedure. The detection limits obtained were within 0.01 and 11.30 μg L⁻¹, with RSDs of 1% to 7% and enrichment factors of between 1 and 385.5, which is adequate for the analyzed samples. Furthermore, the proposed method was applied in the simultaneous determination of the 14 elements mentioned above with a sample throughput of about 13 h⁻¹, thereby, reducing the time of analysis and the volume of reagents and sample required.