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Abstract Hydrogen peroxide (H₂O₂) mediates the biology of wound healing, apoptosis, inflammation, etc. H₂O₂has been fluorometrically imaged with protein‐ or small‐molecule‐based probes. However, only protein‐based probes have afforded temporal insights within seconds. Small‐molecule‐based electrophilic probes for H₂O₂require many minutes for a sufficient response in biological systems. Here, we report a fluorogenic probe that selectively undergoes a [2,3]‐sigmatropic rearrangement (seleno‐Mislow‐Evans rearrangement) with H₂O₂, followed by acetal hydrolysis, to produce a green fluorescent molecule in seconds. Unlike other electrophilic probes, the current probe acts as a nucleophile. The fast kinetics enabled real‐time imaging of H₂O₂produced in endothelial cells in 8 seconds (much earlier than previously shown) and H₂O₂in a zebrafish wound healing model. This work may provide a platform for endogenous H₂O₂detection in real time with chemical probes. 

Rapid palladium (Pd) catalyzed deallylation of an uncoloured reagent within a flowing stream affords a dose dependent colour formation that can be used for convenient online analysis of trace levels of Pd contamination using a modified HPLC instrument. An application to the online sensing of Pd breakthrough from a flow through Pd adsorption cartridge is described. An alternative configuration of the instrumentation allows the rapid (<1 min) and accurate measurement of Pd levels within samples injected via a conventional HPLC autosampler. 

We previously developed Pittsburgh Green homoallyl ether to quantify trace ozone. Independently, problems were reported when the method was used for excess ozone. Here, we discuss the origin of the reported problems and demonstrate that when this method is used according to our previous report, no problems occur.