A novel chelating resin using chitosan as a base material, ethylenediamine-type chitosan, has been synthesized for the first time in the present study, and applied to the collection / concentration of ultratrace amounts of silver in environmental water samples. In the present study, ultratrace amounts of silver collected on the resin were eluted and determined by ICP-MS. The resin packed in a 1-mL mini column could adsorb silver selectively and quantitatively at a flow rate of 2 mL min -1 in the wide pH range from 1 to 8, and silver adsorbed on the resin could be easily recovered by passing 1 M nitric acid as an eluent into the column. High adsorption capacity for silver at pH 5, 0.37 mmol mL -1 of the resin, was achieved, and t 1/2 of the adsorption is less than 5 min. The effect of chloride on the collection of silver was examined by varying chloride concentrations from 10 -4 M to 0.75 M;the results showed that the present resin can be used for the collection / concentration of ultratrace amounts of silver in natural waters, as well as seawater. To ensure the accuracy and the precision of the method, CASS-4 near shore seawater reference material from the NRCC has been analyzed. This is not a certified SRM for silver, but has been used for comparative silver analysis by several groups, who report very similar results to those that are reported here. The developed method using ethylenediamine-type chitosan resin gives 0.7 pg mL -1 of the detection limit when 50-fold enrichment was used. The proposed method was successfully applied to the determination of silver in tap, river, and seawater samples.

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An automated on-line sample-preparation method using a computer-controlled pretreatment system (Auto-Pret AES system) coupled with ICP-AES was developed. In this work, an iminodiacetate chelating resin, packed in a mini-column and installed in the system was employed for the collection/concentration of 13 trace metals, including such toxic metals as Be, Cd, Cr, Cu and Pb. The limits of detection of the proposed method for trace metals were in the range of 0.001 (Be) -0.18 (Pb) ng mL -1 . The enrichment factors for metal ions were about 19 times, when 5 mL of samples were used. The sample throughput was 11 h -1 . The accuracy and the precision of the method were evaluated using river-water reference materials, SLRS-4 from NRCC, JSAC 0301-1 and JSAC 0302 from the Japan Society for Analytical Chemistry. The proposed method can be favorably applied to the collection/concentration of trace metals in natural water samples.

Trace metals in aquatic systems have become a significant topic of concern in various fields associated with water quality, as well as a concern of the general public. Among several kinds of water samples, the determination of trace metals in seawater is the most interesting challenge in analytical chemistry, because of high concentrations of matrix and very low concentrations of analytes.Although inductively coupled plasma-mass spectrometry (ICP-MS) provides most accurate, sensitive and reliable detection for trace metals, its low tolerance of dissolved solids prohibits the direct analysis of trace metals in seawater samples by using this instrument. In the determination of trace metals in seawater by ICP-MS, the transition metals are interfered by polyatomic ions derived from alkali and alkalineearth metals, such as oxide and hydroxide. 1-3 Therefore, preconcentration and matrix separation are required prior to the determination of trace metals by ICP-MS.Sample pretreatment for the collection/concentration of analytes and the removal of matrix and interfering substances using chelating resin, such as commercially available iminodiacetate chelating resin, known as Chelex-100, 4,5 Muromac A-1 6-9 and Toyopearl AF Chelate 650M, [10][11][12] have been used for the determination of transition metals or rare-earth elements in seawater by ICP. The resins, however, can separate only some parts of alkali and alkaline-earth metals from analytes, and such sample matrix as Na can remain with analytes and interfere with the determination of trace metals. Several kinds of chelating resins have been proposed for the determination of transition metals or rare-earth elements in seawater samples. 13-18Since ICP-MS enables multi-element detection simultaneously, it is desirable to determine as many trace elements as possible, including transition metals and rareearth elements, for a comprehensive study of the distribution of trace elements in a marine environment.Among the chelating reagents, ethylenediamine tetraacetic acid (EDTA) is one of the most stable chelating reagents, and can form chelates with a number of trace metal ions. Therefore, EDTA is a suitable chelating moiety for a multianalyte adsorption. Some chelating resins that possess the EDTA moiety have been synthesized using several kinds of polymer matrixes, such as cellulose, 19 glycidyl methacrylate divinylbenzene, 20 or chitosan. [21][22][23] Nowadays, a chelating resin that possesses the EDTA moiety, Nobias Chelate-PA1, has been commercially available (Hitachi High Technologies, Tokyo, Japan). The resin has a good adsorption ability of transition and rare-earth metals, and can separate them from alkali and alkaline-earth metals. However, a high concentration of nitric acid was necessary to recover analytes from the resin, acetone was necessary for cleaning the resin, and furthermore resin particles were very small, which makes it difficult to use in a batchwise or a column pretreatment method, because of the slow flow rate.We are mainly interested in a sorbent b...

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