Synthesis of a chitosan-based chelating resin and its application to the selective concentration and ultratrace determination of silver in environmental water samples

摘要

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 2mLmin~(-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 5,0.37mmolmL~(-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)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 t'o the determination of silver in tap,river,and seawater samples.