基于荧光响应的氨传感膜研究

Study of the Fluorescent Response for Optical Ammonia Sensing Film

利用有机改性溶胶-凝胶的包埋方式，以氨基荧光素（AF）为荧光指示探针制备氨传感敏感膜，考察了AF与γ-[（2，3）-环氧丙氧基]丙基三甲氧基硅烷（GOPS）作用后的膜泄漏度及荧光光谱行为的变化，对氨传感敏感膜的配比进行了一系列的优化，获得了对氨具有高响应灵敏度而对pH无响应的氨光传感敏感膜。利用自行构建的氨传感检测装置对水体中氨进行了检测，传感膜对水溶液NH4的最低检出限为0．3μg·mL^-1，测定的相对标准偏差为4％，线性范围为1～80μg·mL^-1，响应时间（t95）为4min，敏感膜使用寿命大于6个月。

The characters of optical sensing films for ammonia were investigated based on a fluorescent indicator aminofluorescein （AF） immobilization. An organically modified silicates （ORMOSILSs） obtained by copolymerizing various proportions of methyltrimethoxysilane （Me-TriMOS） and tetramethoxysilane （TMOS） was applied. Compared with the fluorescent responses of fluorescein and fluorescein carboxylicate, the fluorescent intensity enhancement of AF for ammonia was found to be caused by the reaction of ammonia with the NH2 group on AF. The reaction may cause the reduction of the interrnolecular self-quenching of AF, resulting in a fluorescence enhancement of sensing film in NH3 solution. Furthermore, the properties and the ammonia- sensing behavior of the film were investigated. The results presented here emphasized the significance of ormosil as a matrix for dissolved ammonia sensing. The detection limit for ammonia in water was 0. 3 μg·mL^-1.