Preparation of a polyclonal antibody against the cadmium–DTPA complex and its application for determination of cadmium

Cadmium (Cd) is considered one of the most hazardous heavy metals. Therefore, it is important to detect Cd. A polyclonal antibody that recognizes Cd–ethylenediamine-N,N,N′,N′-tetraacetic acid complex was prepared via the injection of BALB/c mice with Cd–2-(4-aminobenzyl)-diethylene triamine pentaacetic acid–keyhole limpet hemocyanin. A simple, inexpensive, and reliable indirect competitive enzyme-linked immunosorbent assay (ELISA) based on the polyclonal antibody was developed for determination of Cd. The assay was specific to Cd with an IC₅₀ value of 2.042 μg mL⁻¹ and the detection limit of 0.0135 μg mL⁻¹. Cross-reactivities (CRs) with Cu²⁺, Pb²⁺, Zn²⁺, Mg²⁺, Ca²⁺, Fe²⁺, and Ni²⁺ were below 0.001% except for Hg²⁺ with a CR less than 6%. The recoveries from deionized water were from 92.2% to 116.0%. Results indicated that the ELISA based on the polyclonal antibody would be very promising analytical tools for rapid and sensitive determination of metal ions in the environment.