Ti-containing mesoporous silica packed microcolumn separation/preconcentration combined with inductively coupled plasma-mass spectrometry for the determination of trace Cr, Cu, Cd and Pb in environmental samples

Abstract

Ti-containing mesoporous silica was prepared and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectrometry (UV-Vis) and the N₂ adsorption technique. The adsorption behaviours of Cr(III), Cu(II), Cd(II) and Pb(II) on Ti-containing mesoporous silica were studied and the adsorption mechanism was also investigated by FT-IR and X-ray photoelectron spectroscopy (XPS). With Ti-containing mesoporous silica as the adsorbent, a new method of microcolumn solid phase extraction (SPE) combined with inductively coupled plasma-mass spectrometry (ICP-MS) was established for the determination of Cr(III), Cu(II), Cd(II) and Pb(II) in environmental samples. The parameters affecting extraction and desorption of the target analytes, such as pH, sample flow rate, desorption reagent, desorption flow rate and sample volume, were investigated. Under optimized conditions, the limits of detection (LODs) of Cr(III), Cu(II), Cd(II) and Pb(II) were 19, 39, 7 and 13 pg mL⁻¹ with a preconcentration factor of 10, respectively, and the relative standard deviations (RSDs) varied from 6.1 to 7.3% (n = 7, c = 1 ng mL⁻¹). The developed method was applied to analyze environmental water and soil samples with recovery in the range of 85–119% for the spiked samples. In order to validate the accuracy of the method, certified reference materials of GSBZ50009-88 (environmental water), GBW07429 and GBW07425 (soil sample) were analyzed and the determined values were in good agreement with the certified values. The developed method is simple, rapid, sensitive and suitable for the analysis of trace elements in environmental samples with complex matrices.