Preparation of anti-cadmium-EDTA complex monoclonal antibody and its binding specificity

To develop a convenient immunoassay for the detection of heavy metals, an anti-cadmium EDTA monoclonal antibody (So26G8) was prepared and characterized for its binding affinities towards other metal complexes with EDTA. The cross reactivities of the antibody for metal free EDTA and its complexes with Ca, Cu, Fe, Hg, Mg, Ni, Pb and Zn were less than 0.73% compared with Cd-EDTA. The equibrilium binding constant (K-d) towards Cd-EDTA was determined to be 5.9 X 10(-7) M, and these towards Cu-EDTA, Zn-EDTA and Hg-EDTA were approximately 1.0 X 10(-4) M. In addition, EDTA complexes with the other metals and metal free EDTA were 1000-fold or 10000-fold greater than K(d)s compared with Cd-EDTA. This antibody can be applied to a kinetic exclusion assay to quantify Cd in the presence of EDTA. The dynamic range of the assay was from 4.5 ppb to 2.8 ppm.