Development of a sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for the analysis of cadmium ions in water, soil and rape samples

摘要

Cadmium is classified as a probable human carcinogen. A monoclonal antibody (mAb) against Cd~(2+)-ethylene-diamine-N,N,N′,N′-tetraacetic acid (EDTA) complex was generated by immunising mice with the conjugate of Cd~(2+)-EDTA-aminobenzyl-ovalbumin. An indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed and applied for the analysis of Cd~(2+) in water, soil and rape samples. The half-maximum inhibition concentration and detection range were 2.59 ng/ml and 0.20–40 ng/ml, respectively. The assay cross-reactivities with non-target metal-EDTA complexes were all below 1%, except Mn~(2+) (2.9%) and Hg~(2+) (1.6%). The average recoveries of Cd~(2+) in tap water, Jingmi Canal, Xiaoqing River (at concentrations of 2–20 ng/ml), soil (0.25–10 ug/g) and rape (0.1–1.2 ug/g) samples were 103.0%, 101.0%, 103.0%, 82.4% and 93.7%, respectively. Concentrations of Cd~(2+) measured by this immunoassay agreed well with those determined by graphite furnace atomic absorption spectroscopy (GFAAS) (k =1.1225, r ~(2)=0.9873).The established icELISA was a quick, reliable and sensitive method to detect Cd~(2+) in environmental and vegetable samples.