Hydrogen peroxide stabilization with silica xerogel for paper-based analytical devices and its application to phenolic compounds determination

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BackgroundHydrogen peroxide is a key reagent in many analytical assays. At the same time, it is rather unstable and prone to evaporation. For these reasons, its application in sensors requiring reagents in solid state, for example in paper-based microfluidics, is hindered. Usually in paper-based analytical devices reagents are stored in a dried form within paper matrix until the device is used. This approach is not feasible in case of hydrogen peroxide. Here, hydrogen peroxide stabilization on paper with the aid of silica xerogel was studied and optimized to create long-term stable systems which rapidly deliver hydrogen peroxide. ResultsThe variables affecting hydrogen peroxide stability such as gelation time, silica to H2O2 ratio, type of solid support and storage conditions were optimized to find the combination of variables providing stable H2O2 concentration for the longest time possible. Such paper-silica-H2O2 composites allow to maintain steady hydrogen peroxide concentration for at least 27 days in the optimal conditions. Hydrogen peroxide is rapidly released from silica-paper matrix within a few minutes upon contact with water, without any byproducts. The obtained systems were characterized using scanning electron microscopy with energy dispersive spectroscopy and infrared spectroscopy, revealing that silica is present as a thin film covering cellulose fibers. Finally, to test the developed hydrogen peroxide stabilization method in real sensing scenario, a proof-of-concept paper-based sensor was created for phenolic content determination in fruits and wine. SignificanceThe outcome of this research will open new avenues in the development of user-friendly, long-term stable paper-based analytical devices which utilize hydrogen peroxide as one of reagents. Owing to the fact, that silica matrix is insoluble in water, the proposed H2O2 stabilization method is compatible with most detection schemes without the risk of interfering with the assay.