An organically modified sol–gel membrane for detection of mercury ions by using 5,10,15,20-tetraphenylporphyrin as a fluorescence indicator

A new optical sensor membrane for sensing of Hg2+ in aqueous solution has been developed by using (5,10,15,20-tetraphenylporphyrin, H2tpp) as a lipophilized indicator, which was dissolved in an organically modified sol–gel. The method for preparation of this organically modified sol–gel membrane and its characteristics were investigated in detail. The fluorescence quenching of the sol–gel membrane by Hg2+ showed a linear response over the Hg2+ concentration range of 5.0 × 10−6 to 1.0 × 10−4 mol/l with a detection limit of 3.6 × 10−6 mol/l, and the good stability, reversibility, long lifetime and short response time could be obtained.