γ-MPTMS modified nanometer-sized alumina micro-column separation and preconcentration of trace amounts of Hg, Cu, Au and Pd in biological, environmental and geological samples and their determination by inductively coupled plasma mass spectrometry

Nanometre-sized alumina was chemically modified with gamma-mercaptopropyltrimethoxysilane (gamma-MPTMS). The modified nanometer-sized alumina was characterized by X-ray power diffusion (XRD), X-ray photoelectron energy spectrometer (XPS) and diffuse reflectance infrared Fourier transform spectroscopy ( DRIFTS) before it was used as solid phase adsorption material for the inductively coupled plasma mass spectrometry (ICP-MS) determination of trace amounts of Hg, Cu, Au and Pd. The effects of pH, sample flow rate and volume, elution solution and interfering ions on the recovery of the analytes have been investigated. Under the optimized conditions, the adsorption capacity of modified nanometer-sized Al2O3 was found as 10.4, 16.3, 15.3, and 17.4 mg g(-1) for Hg, Cu, Au and Pd, respectively. The limits of detection were as low as 0.066 and 0.49 ng L-1 for Cu and Hg with a concentration factor of 100 times, and 0.46 and 0.26 ng L-1 for Au and Pd with a concentration factor of 200 times. The developed method has been applied to the determination of trace Hg and Cu in biological and environmental certified materials and Au and Pd in geological certified materials, and the determined values were in a good agreement with the certified values.