Gold nanoflowers based colorimetric detection of Hg2+ and Pb2+ ions.

An optical detection method based on the interaction of gold nanoflowers with Hg(2+) and Pb(2+) has been described. After interaction, gold nanoflowers change the color from violet to wine red. The nanoflowers are capable of determining Hg(2+) and Pb(2+) over a dynamic range of 1.0 × 10(-6) and 1.0 × 10(-5)M, respectively. The response time of nanoflowers depends on the concentration of ions. The presence of both Hg(2+) and Pb(2+) ions in the mixture having Au nanoflowers induced color changes of the solution within several seconds even at 1.0 × 10(-6)M. Common metal ions were chosen to investigate their interference in Hg(2+) and Pb(2+) detection, and the concentration of each metal ion studied was 1.0 × 10(-5)M. Other metallic ions could not induce color change even at 1.0 × 10(-5)M. The feasibility of our method to detect Hg(2+) and Pb(2+) ions at high concentration in real water samples was verified. Water samples were from our own laboratory and no pretreatment was made. As the particles are stable they can be used for more than 3 months without observing any major deviation.