A high-precision strategy for quantitative determination of trace-level free water in aviation fuel: ACQ-based...

As one common contaminant in aviation fuel, the free water poses significant risks to aircraft safety. The currently adopted quantitative technology, Karl Fischer (KF) method, always suffers from an operational complexity and considerable sampling errors when determining trace-level free water. To address this issue, a water-sensitive filtration membrane based on the aggregation-caused quenching (ACQ) effect of sodium fluorescein (FS) was reported in this work. Upon contact with water, the FS-coated membrane exhibited immediate fluorescence activation, achieving a detection limit as low as 1 ppm for trace-level free water. A linear correlation between fluorescence intensity and water concentration enabled quantitative determination in the range of 1-30 ppm, with a relative standard deviation (RSD) of less than 3%. This accurate, rapid, and in situ fluorescent detection system meets the urgent demand of the aviation industry for a novel analytical approach. It not only broadens the application scope of fluorescence sensors but also holds significant promise for aviation fuel quality evaluation, thereby enhancing the precision and reliability of flight safety assurance.