Selective chemiluminescent sensor for detection of mercury(II) ions using non-aggregated luminol-capped gold nanoparticles

A selective chemiluminescent sensor was developed for the detection of mercury(II) ions (Hg 2+ ) in environmental water and soil supernatant samples using non-aggregated luminol-capped gold nanoparticles (AuNPs). Luminol-capped AuNPs can react with silver nitrate (AgNO 3 ) under alkaline environment , generating a strong chemiluminescence (CL) emission because AuNPs had excellent catalytic activity for luminol-AgNO 3 CL system. However, when Hg 2+ was added to the solution of luminol-capped AuNPs, it would be adsorbed on the surface of luminol-capped AuNPs according to the inherent affinity of AuNPs for Hg 2+ . The presence of Hg 2+ significantly inhibited the catalytic activity of AuNPs, leading to CL quenching. With the increasing of Hg 2+ concentration, the CL intensity gradually decreased. Under the optimal detection conditions, the developed CL sensor showed a good linear relationship in range of 10–600   nM with a limit of detection of 1   nM at a signal-to-noise ratio of three which was below the maximum allowable concentration for Hg 2+ in drinking water (10   nM) defined by United States Environmental Protection Agency. Also, the developed CL sensor exhibited high selectivity toward Hg 2+ over other environmentally relevant metal ions at high concentrations (500   μM).