Adsorbility of Lead, Cadmium and Sodium on the Chelating Resin, Chelex-100 and Its Application to AAS Determination of Lead, Cadmium in High-Salt Food

The distribution coefficients (Kd) and adsorption capacity of Pb2+, Cd2+ and Na+ on Chelex-100, a chelating resin in media of different pH values were studied. It was found that in a medium of pH 1-8, the Kd of Na+ was less than 3, while the Kd of Pb2+ and Cd2+ were more than 104, hence, Pb2+ and Cd2+ were adsorbed strongly on the resin, while Na+ was not adsorbed. And Pb2+ and Cd2+ were completely eluted from resin with 0.16 mol·L-1 HNO3 as eluent. Based on these facts, a method of AAS determination of cadmium and lead in high-salt food was proposed. Sample of high-salt food was analyzed by the proposed method, giving values of recovery in the range of 93.1%-102%, and values of RSD′s (n=5) in the range of 0.5%-3.4%.