Analytical Sciences

On-line Preconcentration System Using Mini-column Packed with a Chelating Resin for the Characterization of Seasonal Variations of Trace Elements in Seawater by ICP-MS and ICP-AES

Takashi SUMIDA,* Tetsuya NAKAZATO,** Hiroaki TAO,** Mitsuko OSHIMA,*** and Shoji MOTOMIZU***

*Kochi Prefectual Industrial Technology Center, 3992-3 Nunoshida, Kochi 781-5101, Japan
**National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba 305-8569, Japan
***Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan

An on-line column preconcentration technique coupled with inductively coupled plasma-mass spectrometry (ICP-MS) and -atomic emission spectrometry (ICP-AES) was developed using a mini-column (ca. 3 mm i.d., 40 mm length), that was packed with chelating resin (0.2 g) of iminodiacetic acid groups, Muromac A-1. After the preconcentration step, the column was washed with ammonium acetate buffer (pH 5.5) and water to remove major elements, such as Ca and Mg, and then eluted with 4 ml of 2 mol l^-1 nitric acid. Eleven trace elements (Al, V, Fe, Co, Ni, Cu, Zn, Cd, Pb, Th and U) in seawater were determined by ICP-MS/AES. Recoveries for most of the elements tested were over 90%, although those for Al, V and Th were around 70%. The accuracy of the proposed method was evaluated by analyzing a standard reference material of seawater (NASS-4, NRC Canada). The values of Fe, Co, Ni, Cu, Zn, Cd and Pb obtained with the present method showed good agreement with the certified values as judged from the standard deviation. The method was successfully applied to characterize seasonal variations of trace elements in deep seawater (DSW) and surface seawater (SSW). In addition, no serious decrease in analytical performance of the present column system was observed during the experimental period of about 1 year.

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