Determination of trace elements in samples with high salt content by inductively coupled plasma mass spectrometry after solid-phase preconcentration

Abstract

A method for solid-phase extraction (SPE) using nanometer-sized silica modified with N-[2-aminoethyl]-3-aminopropyltrimethoxysilane (AAPTS) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was proposed in this work for analysis of Ni(II), Cu(II), Ga(III), Cd(II), Pb(II), and Bi(III). It was noted from zeta potentials that the absorptivity of the modified nanoparticles could be partially attributed to the electrostatic interactions of amino groups in alkaline conditions. Elemental ions were adsorbed at a pH of 9.0 and then eluted with 1 mol/L nitric acid and 0.5% citric acid. Effects of enrichment time, sample flow rate, and coexisting ions were also investigated. Using the same instrument conditions, higher recovery of elements in synthetic seawater after solid-phase extraction was achieved compared to directly diluting 50 times with 1% nitric acid. This method was successfully applied for the determination of trace metal ions (Ni, Cu, Ga, Cd, Pb, and Bi) in milk powder samples.