LAUSR

Water is one of the most widespread impurities and contaminants for pharmaceuticals and chemical products. A simple, fast and reliable water assay method is of high significance for pharmaceutical and chemical manufacturing industry. In this work, lanthanide metal-organic framework Eu-dipicolinic acid/2-aminophthalic acid (Eu-DPA/PTA-NH2) was prepared as a double-color ratiometric fluorescent water sensor, which shows ultra-sensitive (limit of detection 0.01% v/v) and linear broad-range (0-100% v/v) response to water. An innovative analytical device based on one-to-two logic gate was constructed by using the water content and the two fluorescence responses as the input and output signals, respectively. The direct analysis of water content can be achieved by the four output types, NOT (0, 1), PASS 0 (0, 0), PASS 1 (1, 1) and YES (1, 0). Importantly, the MOF-loaded fiber paper was prepared as a microsensor, and a water assay tube was designed for rapid water detection of solid pharmaceuticals via ratiometric chromaticity, coupled with a portable visual determination device. The paper-based microsensor is response-rapid (20 s), long-term stable (at least 30 days), and can achieve the accurate (relative error < 9.8%) visual assay of trace water in solid pharmaceuticals. To our knowledge, this is the first time to report a MOF-based double-color ratiometric fluorescent water sensor, a water analytical logic device and a paper-based water microsensor for point-of-care visual water assay in solid samples via ratiometric chromaticity.