Development of an immunochromatographic strip and its application in the simultaneous determination of Hg(II), Cd(II) and Pb(II)

Heavy metal contamination in water has attracted great attention worldwide. The development of a simple, inexpensive, mobile, and rapid analytical technique for simultaneous detection of Hg(II), Cd(II) and Pb(II) is still a challenging analytical problem. Here we describe an immunochromatographic strip based on specific monoclonal antibodies (McAbs)-labeled gold nanoparticle for rapid, simultaneous, and specific determination of Hg(II), Cd(II) and Pb(II) in water samples. In the method, Hg(II)-ITCBE-BSA, Cd(II)-ITCBE-BSA, Pb(II)-ITCBE-BSA and goat anti-mouse IgG antibody were coated on the NC membrane as test lines (TLs) and control line (CL), respectively. Anti-Hg(II)-ITCBE McAb-particle, anti-Cd(II)-ITCBE McAb-particle and anti-Pb(II)-ITCBE McAb-particle were applied to the conjugate pad. The flow of the McAb-particle conjugates along the strip resulted in characteristic TL inversely proportional to the concentration of metal ion, enabling visual and simultaneous determination of Hg(II), Cd(II) and Pb(II) in a single strip. The visual limits of detection (LODs) for the simultaneous determination of Hg(II), Cd(II) and Pb(II) were 8 nM, 6 nM and 6 nM, respectively. The assay can be performed within 10 min. The novelty of the developed immunochromatographic assay is simultaneous determination of multiple metal ions using a single strip.