To confirm the practical sensing effect, our Hg2+detection sys-tem is used to analyze the tap water and lake water. Fig. 7 showsthe photograph of our detection systems incubated with differ-ent concentrations of Hg2+. The concentrations of Hg2+in the tapwater or lake water are respectively 0.34 and 0.89 M determinedby ICP–AES. Through comparing the color of the detection sys-tems containing real water samples with that of the detectionsystems containing standard concentrations of Hg2+, the Hg2+con-centrations in tap water or lake water samples are respectivelydetermined to be around 0.40 M or 0.80 M, which are both closeto those determined by ICP–AES. Furthermore, the added amount and the detected amount (by our detection system using UV–vis spectroscopy) of Hg2+in the real water samples are shown in Table 1. We can see both values are very similar, which indicates the feasibility and sensitivity of our Hg2+detection system using colorimetry and UV–vis spectroscopy. These results reinforce that our