纳米SiO2富集水样重金属镉-hicELISA检测方法的建立

目的:探究纳米SiO₂富集分离水样中Cd2+的条件，制备抗Cd2+单克隆抗体，建立水样中痕量Cd2+异源性间接竞争ELISA（heterologous indirect competitive ELISA，hicELISA）快速检测方法。方法:以纳米SiO₂富集、EDTA-2Na竞争洗脱Cd2+，ICP法测定处理过程中的Cd2+含量。人工合成Cd-ITCBE-BSA免疫Balb/C小鼠，制备Cd2+单克隆抗体。人工合成异源性包被抗原，建立镉离子hicELISA检测方法。结果:纳米SiO₂对Cd2+的吸附容量为13.3 mg/g，富集倍数可达20倍，EDTA-2Na可有效洗脱被富集的Cd2+。以Cd-ITCBE-BSA为免疫原，小鼠血清效价达到1:1.28×104；腹水效价为1:2.0×105，亲和力Ka为8.1×108 L/moL。以Hg-ITCBE-OVA包板建立的hicELISA检测限为2.9 μg/L，与Hg2+、Cu2+、Zn2+、Pb2+、Cr3+、Mo6+、Fe3+、Co2+ 无明显交叉反应。在湖水、自来水、超纯水样品中镉的加标回收率为92.47%~102.86%。结论:建立的纳米SiO₂富集重金属镉-hicELISA检测方法灵敏、特异、准确，能用于水样中镉离子的检测。

Determination of Cadmium in Water Samples by Nano-SiO2 Preconcentration with hicELISA

Objective: Explore the conditions of preconcentration and separation of Cd2+ in water samples by nano-SiO₂, prepare monoclonal antibody against Cd2+ and establish a rapid detection method of trace Cd2+ in water samples by heterologous indirect competitive ELISA (hicELISA). Methods: Cd2+ was preconcentrated by nano-SiO₂ and eluted by EDTA-2Na. The content of Cd2+ was determined by ICP. Balb/C mice were immunized with Cd-ITCBE-BSA to prepare Cd2+ monoclonal antibody. The heterologous coating antigen was synthesized to establish the detection method of cadmium ion hicELISA. Results: The adsorption capacity of Nano-SiO₂ for Cd2+ was 13.3 mg/g, and the enrichment multiple was 20 times. EDTA could be used as the effective eluent for the pretreatment. Using Cd-ITCBE-BSA as immunogen, the titer of serum was 1:1.28×104, The titer of mAb in ascites was 1:2.0×105 and the affinity constantwas 8.1×108 L/mol. The detection limit of hicELISA was 2.9 μg/L. There was no significant cross reaction with Hg2+, Cu2+, Zn2+, Pb2+, Cr3+, Mo6+, Fe3+, Co2+. The recoveries of cadmium in lake water, tap water and ultrapure water were 92.47%~102.86%. Conclusion: The hicELISA method was sensitive, specific and accurate, and could be used for the detection of cadmium in water samples.