Highly Selective and Sensitive Colorimetric Sensor of Cyromazine Based on Gold Nanoparticles

In this paper, a highly sensitive and low cost optical sensor of cyromazine was prepared and used to the colorimetric detection using bare gold nanoparticles (Au NPs). Based on the distance-dependent optical properties of Au NPs, the presence of cyromazine could rapidly induce the aggregation of gold nanoparticles, thereby resulting in red-to-deep blue color change. The concentration of cyromazine was determined with a limit of detection (LOD) lower than 1 μg/L by the naked eyes and the sensitivity could be enhanced by the adjustment of ion strength and pH. The highest selectivity was obviously achieved with an absorption ratio (A₆₄₀/A₅₂₀) greater than 0.9. Moreover the possible underlying mechanism was discussed.