Sol-gel-based optical sensor for the detection of aqueous amines.
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.
Korent
Spela Mojca
SM
Center of Sensor Technology, Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia.
Lobnik
Aleksandra
A
Mohr
Gerhard J
GJ
D000588:Amines / Q000032:analysis*; D005782:Gels; D055095:Optics and Photonics; D012680:Sensitivity and Specificity; D014867:Water
D000588:Amines; D005782:Gels; D014867:Water