Cadmium Rapid Test Kit using Cadmium Purification Column and Cadmium Immunochromatography

Abstract

A simple and rapid immunochromatography system for the detection of cadmium (Cd) in rice has been developed. The produced anti‐Cd‐ethylenediaminetetraacetic acid (EDTA) antibody exhibited equilibrium dissociation constant (Kd) for Cd‐EDTA at 1.3×10−8 M, which was almost 100‐fold tighter than Kds for the other tested EDTA–metal complex. Cadmium in rice was extracted by hydrochloric acid (HCl) and the extract was introduced into a column to remove co‐existing metals (such as zinc, manganese, and magnesium) while retaining Cd. After the pretreatment, immunochromatography could detect Cd in the range from 0.01 to 0.1 mg L−1. Fifty brown rice samples were tested with the column treatment and the immunochromatography assay. The estimated Cd concentrations from the assay were evaluated by the comparison to the results of nitrate treatment and inductively coupled plasma–atomic emission spectroscopy (ICP‐AES) analysis for the samples. Two measurements were highly correlated, with a correlation coefficient of 0.94. A test kit including this immunochromatography and pretreatment system is expected as an on‐site screening device that allows quick testing for Cd‐contaminated foods, crops, water, and soil.