Selective determination of mercury (II) in coastal water using bio-functionalized gold nanoparticles

Abstract

The key to simple and rapid detection of a large volume of samples lies in the hands of solution-based nanomaterial sensors. Quantification of mercury in the river and coastal water is analytically challenging due to the potential interference of the matrix. In this endeavor, lysine-capped gold nanoparticles (Lys-AuNPs) based colorimetric sensors are demonstrated here towards efficient detection of trace amounts of mercury ions (Hg2+) in coastal and estuarine water. The colorimetric behavior of Lys-AuNPs is related to surface plasmon resonance (SPR). During analysis, interestingly a decrease in the intensity of the original SPR peak at 530 nm was observed, with the concomitant appearance of a new peak at a longer wavelength due to agglomerated Lys- AuNPs. Developed sensors exhibit excellent performance in different environmental samples with high selectivity towards Hg2+ ions in the presence of other metal ions. For the analysis of coastal water samples, a low value of regression coefficient was observed due to the potential interference of salt in the sample. To overcome this, matrix-matching experiments were carried out. Developed Lys- AuNPs show good selectivity towards Hg2+ in matrixed matched diluted coastal water samples. With a sensitivity of 0.02 ppm, the sensor can be utilized to screen large numbers of coastal water samples for their Hg2+ content to satisfy coastal regulation norms. As a whole, this method is simple, sensitive, selective, cost-effective and can be used to screen large numbers of samples across the coastal area for monitoring Hg2+ concentration.