Induction with column preconcentration

The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS) and must be eliminated. Consequently, preconcentration techniques used to lower detection limits must also exclude these elements. Techniques based on solvent extraction of hydrophobic chelates and column preconcentration using Chelex 100 achieve these objectives and have been widely used with GFAAS. 

J.-H. Wang, E.H. Hansen, Interfacing sequential injection on-line preconcentration using a renewable micro-column incorporated in a Tab-on-valve system with direct injection nebulization inductively coupled plasma mass spectrometry, J. Anal. At. Spectrom. 16 (2001) 1349. 

S. Hirata, Y. Umezaki, and M. Ikeda, Determination of Chromium(III), Titanium, Vanadium, Iron(III), and Aluminum by Inductively Coupled Plasma Atomic Emission Spectrometry with an On-Line Preconcentrating Ion-Exchange Column. Anal. Chem., 58 (1986) 2602. 

In this vein, many appHcations have appeared in the literature on speciation of oxidation states, such as Cr(m)/Cr(VI), Fe(n)/Fe(m), As(III)/As(V), Se(IV)/ Se(VI). Also, FIA techniques have been used to preconcentrate Sn, Hg, and Pb organometallics mainly from natural waters, sediment, and soil extracts. In particular great interest has been focused into the speciation of chromium oxidation states in water samples at very low level (nanograms per liter). A FI system with a minicolumn of acidic preconcentration and inductively coupled plasma optical emission spectrometry (ICP-OES) for final detection was developed for a rapid speciation of Cr(VI) and Cr(III) in waters. On sample injection, Cr(VI) is retained in the alumina column whilst Cr(III) is not passing directly to the atomic detector. Afterwards, the retained Cr(VI) is eluted by injection of ammonium hydroxide, as shown in Figure 5, and its analytical signal of emission in the ICP-OES is registered. 

J. Yin, Z. Jiang, G. Chang, and B. Hu. Simultaneous on-line preconcentration and determination of trace metals in environmental samples by flow injection combined with inductively coupled plasma mass spectrometry using a nanometer-sized alumina packed micro-column. Analytica Chimica Acta 540 333-339, 2005. 

Kumagai, H.,Yamanaka, M., Sakai,T., andYokoyama.T. (1998). Determination of trace metals in sea-water by inductively coupled plasma mass spectrometry interfaced with an ion chromatographic separation system Effectiveness of nitrilotriacetate chelating resin as the column stationary phase for preconcentration and elimination of matrix effects. Anal. At. Spectrom. 13(6), 579. 

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