Development of a mercury ion-selective optical sensor based on fluorescence quenching of 5,10,15,20-tetraphenylporphyrin

A selective optical chemical sensor for mercury ion based on a lipophilized sensing material (5,10,15,20-tetraphenylporphyrin, H2tpp) dissolved in a p lasticized poly(vinyl chloride) (PVC) membrane has been developed. H2tpp im mobilized in the PVC membrane acts not only as a selective host molecule fo r Hg2+, but also as a fluorescing transducer. The sensing mechanism involve s the extraction of Hg2+ from aqueous sample solution to organic membrane p hase and the formation of a metalloporphyrin complex between H2tpp and Hg2, which results in the fluorescence quenching of H2tpp. The optode membrane containing H2tpp reversibly responds to Hg2+ and shows extremely high sele ctivity to Li+, Na+, K+, Mg2+, Cd2+, Cu2+, Fe3+, Ag+ and Pb2+. The detectio n limit for Hg2+ is 4.0 x 10(-8) mol/l at pH 8.0. The response characterist ics of the sensor including dynamic range, reversibility, reproducibility, response time and lifetime are discussed in detail. This sensor has been us ed for the determination of mercury ion in water samples containing potenti al interferents with satisfactory recovery. (C) 2001 Elsevier Science B.V. All rights reserved.