Application of a Poly(Hexafluoropropyl-Co-Tetrafluoroethylene) Thin-Film Architecture for Aqueous O₂ Quantification

Compared to electrochemical methodologies, detection and quantification of O₂ with optical means has been regarded as more advantageous. Among the optical approaches that have been exploited, fluorescence quenching schemes have attracted significant attention. More recently, several authors have used time-resolved fluorescence in concert with quenching schemes to sense O₂. We report a new quenching-based architecture to detect dissolved O₂ in water. The system is composed of a fluoropolymer film, namely) (FEP), that has been subjected to a radio-frequency glow discharge plasma to introduce -OH groups, modified further with aminopropyl-triethoxysilane (APS) to produce an aminated surface, and subsequently reacted with an activated pyrene (Py) residue to form FEP-APS-Py. In a sample cell configuration this system exhibits a sensitivity to aqueous O₂ as high as 863 ± 28 M⁻¹ and a detection limit on the order of 10 μM O₂. If β-cyclodextrin is added to the aqueous solution, the sensitivity to O₂ is enhanced further. Slow time-dependent reconfiguration of the FEP-APS-Py surface is the major drawback of this system.