AN OPTIC-FIBER SENSOR FOR METRONIDAZOLE BASED ON THE FLUORESCENCE QUENCHING OF A COPOLYMER BOUND FLAVONE DERIVATIVE

A new optic-fiber sensor for metronidazole (1-(2-hydroxyethyl)-2-methy l-5-nitromidazole) has been fabricated with a fluorescent copolymer pr epared from 3-hydroxy-4'-N,N-dimethylaminoflavone methacrylate, methyl methacrylate, and butyl acrylate (PFMB). The sensing is based on the quenching of the fluorescence of a PFMB membrane by metronidazole. An orthogonal-experimental design was used for the membrane composition o ptimization. The present sensor responds linearly to metronidazole in the concentration range of 3.00x10(-5) mol l(-1) to 3.00x10(-3) mol l( -1) with a detection limit of 1.00x10(-5) mol l(-1). The response is o n the order of 30 s. The lifetime is enhanced by covalently immobilizi ng the flavone derivative to the membrane, which hinders leaching of t he dye from the membrane. With the described sensor, good reproducibil ity and reversibility have been realized. The sensor has also shown go od selectivity over common inorganic anions and cations, and some phar maceuticals. It can be used for the direct determination of metronidaz ole in commercial pharmaceutical preparations; the obtained results we re in agreement with those obtained by a pharmacopoeia method.