Visual Detection of Iodide Ion by Total Internal Reflection of Single Oxygen Microbubble
2020
Lei, Yuting | Yu, Ling | Huang, Wei | Yu, Haili | He, Yi
Facile and rapid detection of iodide ion (I–) has a substantial impact on nuclear chemistry, environmental monitoring, and other fields. Here, we report a new method for visual detection of I– at the single-microbubble level. This assay utilizes the total internal reflection of single O₂ microbubble at the O₂ microbubble–glass interface to produce the evanescent wave, which is imaged by a dark-field microscope. The diameter of the single O₂ microbubble in the H₂O₂ aqueous solution increases after introduction of I–, thanks to its catalytic ability toward H₂O₂ decomposition. With this assay, I– is quantitatively determined based on the diameter change of the single O₂ microbubble, along with micromolar level sensitivity, and the corresponding dynamic ranges from 0.08 to 1 mM. Impressively, this visual assay possesses high selectivity owing to the specific catalytic activity of I–, and it is successfully applied for detection of real water samples, showing satisfactory recovery rates. Our study opens up a single O₂ microbubble analytical platform with a high spatial resolution because of the small size of the microbubble, which holds great promise in chemical and environmental applications.
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