title: Sol-gel-based optical sensor for the detection of aqueous amines.
abstract: We present an optical sensor for the detection of aqueous amines obtained by incorporating chromoionophore XV (ETH(T) 4001) into sol-gel thin films. Acid- and base-catalyzed sol-gel processes were studied to prepare stable ormosil layers using various amounts of organically modified sol-gel precursor such as methyltriethoxysilane (MTriEOS). The sensor layers were coated with a protective layer of microporous white polytetrafluoroethylene (PTFE) in order to prevent interference from ions and ambient light. The measurements were carried out in a flow-through cell in the reflection mode. Acid-catalyzed ormosil layers (pH 1) based on the copolymerization of tetraethoxysilane (TEOS) and MTriEOS did not show any change in signal upon exposure to aqueous amine solutions, while base-catalyzed sensor layers (pH 3 and 13) showed significant changes in signal. The response time (t (100)) for the base-catalyzed sensor layer L3 (pH 13) upon exposure to different solutions containing 0-608 mmol L(-1) aqueous propylamine was 20-30 s, the regeneration time was 70 s and the detection limit was 0.1 mmol L(-1). The sensor response was reproducible and reversible. The porous ormosil layers permit dry sensor storage conditions.
authors: Center of Sensor Technology, Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia.
authors: Spela Mojca
authors: SM
authors: Korent
authors: Aleksandra
authors: A
authors: Lobnik
authors: Gerhard J
authors: GJ
authors: Mohr
mesh_terms: D000588:Amines / Q000032:analysis*; D005782:Gels; D055095:Optics and Photonics; D012680:Sensitivity and Specificity; D014867:Water
chemical_list: D000588:Amines; D005782:Gels; D014867:Water