A Picric Acid Optical Chemical Sensor Based on Fluorescence Quenching
Long Liping 1, Wang Kemin 2, Yang Ronghua 2, Yang Xiaohai 2 1 (Department of Chemistry & Environmental Engineering, Hunan City College, Yiyang 413049) 2 (College of Chemistry & Chemical Engineering, Hunan University, Changsha 410082)
An optical chemical sensor has been developed for the determination of picric acid based on reversible fluorescence quenching of N,N′-dibenzylaniline-3,3′,5,5′-tetramethylbenzidine(TMBD) immobilized in a plasticized polyvinyl chloride (PVC) membrane. The optimum membrane of the sensor consists of 50 mg of PVC, 100 mg of bis (2-ethytbexyl) sebacate (DOS) and 6.0 mg of TMBD. The maximum response of the optode membrane for picric acid was obtained in H 2SO 4 solution of 0.12 mol/L. With the optimum conditions described, the proposed sensor responds linearly in the measuring range of 2.10×10 -7 to 4.00×10 -4 mol/L, and has a detection limit of 7.8×10 -8 mol/L. The response time of the sensor is less than 40 s. In addition to high reproducibility and reversibility of the fluorescence signal, the sensor also exhibits good selectivity. Some common anions and cations do not interfere. It was applied to the direct determination of picric acid in synthetic water samples and indirect determination of cinchonine. The results were in good agreement with the literature method.