Development Of Gold Immunochromatographic Assay For Rapid Detection Of Cadmium Ion And Adsorption Of Attapulgite To Cadmium Ion

The pollution caused by heavy metal cadmium has been a continuing concern by human. Especially in recent years, cadmium pollution accidents are happening all of world with increasing frequency. It has posed a great threaten to environmental safety and human health. Therefore, it is essential to develop a quick, inexpensive, simple to perform, and reasonably portable method for the real-site determination of cadmium in water samples.Colloidal gold immunochromatography strip was prepared for rapid determination of residual cadmium ion in water samples. Competitive assay was adopted in this study. Colloidal gold binding cushion was coated with anti-Cd2+-EDTA monoclonal antibody-colloidal gold complex, and cellulose nitrate film was coated with synthetic Cd-iEDTA-BSA to form the test (T) band. The determination result was observed 3-5 min later and judged according to the color of T band. The prepared strip was verified for sensitivity, specificity and stability, and then used for determination of water samples containing cadmium standard. The minimum detection limit of cadmium ion by the prepared strip was 1 mg/L. Except that with Hg2+, no cross reactions with other metal ions such as Pb2+, Ca2+ and Cu2+ were observed. The strip showed good stability after storage at room temperature for 2 weeks. Colloidal gold immunochromatography is easy to handle, stable and reliable, which may be used as an effective tool for field determination and monitoring of cadmium ion in water samples. The major advantages of the one step strip test were that results could be obtained within 5 min and that all needed reagents were included in the strip.For its low costs and great performance in the adsorption of many pollutants, attapulgite has been obtained increasing scientific attention. The attapulgite used in this study is from Xuyi in Jiangsu province. Adsorption of cadmium ion by original attapulgite and modified attapulgites with hydrochloric acid were conducted by batch experiments. The adsorptive capacity of the modified attapulgite toward to Cd2+ was studied. The results showed that Cd2+ removal efficiency is 98% under the optimum with 0.15 g adsorbent, the pH=6 and 5 min adsorption equilibrium time. It can be seen that the adsorption of cadmium in water samples with modified attapulgite is a good technique for the removal of cadmium.