We have devised rapid analyses for mercury exploiting the high affinity of dithiocarbamate chelators for the mercuric ion. Our first assay is based on a sandwich chelate formed by a ligand supported on the well of an ELISA plate, Hg2+ ion of the investigated sample, and another ligand bound to a reporter enzyme. The second assay utilizes competitive binding of the analyte Hg2+ ions versus an organomercury conjugate to a chelating conjugate. Low ppb sensitivity and high selectivity for Hg2+ ions have been achieved in our pilot studies.