Miniaturized Separation‐Sensing Tandem Enabled by Fluorescent Monoliths

Discriminative sensing for mixture by either fluorescent sensor or other sensors remains a challenge. This issue is attributed to the absence of a separation unit prior to the sensor. Here, we report a new sensing medium, named porous fluorescent monolith, which can separate mixture and meanwhile be integrated into a sensor for discriminative detection. The fluorescent monoliths are prepared via polymerization of 4,4',4″,4^‴-(ethene-1,1,2,2-tetrayl)tetrabenzaldehyde with diamines. Their photophysical property and hierarchical porosity are systematically studied. On this basis, we set up a separation-sensing platform and realize quantitative analysis for trace water in methanol, a sarin simulant, perfluoroalkyl compounds, and metal ions. The separation-sensing platform furthermore demonstrates baseline separation for benzene, toluene, ethylbenzene, and xylene, with limit of detections of 86, 54, 19, and 58 ng, respectively. To our knowledge, this is the first time that a fluorescent monolith is used to realize a separation-sensing tandem. We anticipate our findings will provide a promising strategy for producing portable devices with the on-site discriminative sensing ability for real samples.