An Optic-Fiber Sensor for Metronidazole Based on the Fluorescence Quenching of a Copolymer Bound Flavone Derivative

Abstract

A new optic-fiber sensor for metronidazole (1-(2-hydroxyethyl)-2-methyl-5-nitromidazole) has been fabricated with a fluorescent copolymer prepared 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 optimization. The present sensor responds linearly to metronidazole in the concentration range of 3.00×10^-5 mol l^-1 to 3.00×10^-3 mol l^-1 with a detection limit of 1.00×10^-5 mol l^-1. The response is on the order of 30 s. The lifetime is enhanced by covalently immobilizing the flavone derivative to the membrane, which hinders leaching of the dye from the membrane. With the described sensor, good reproducibility and reversibility have been realized. The sensor has also shown good selectivity over common inorganic anions and cations, and some pharmaceuticals. It can be used for the direct determination of metronidazole in commercial pharmaceutical preparations; the obtained results were in agreement with those obtained by a pharmacopoeia method.