Use of Optically Transparent Membranes for Preconcentration and Direct Phosphorimetric Determination of Pharmaceutical Flumequine

A preconcentration membrane for the retention and phosphorimetric determination of flumequine is proposed. The membrane has a circular zone adhering to the surface of a polyester strip, which constitutes the preconcentration area where the analyte is retained by absorption from a solution that contains it. The phosphorescence intensity emitted by the flumequine can be measured directly in the solid phase, at λexc = 358 nm and λem = 459 nm. The variables that influence the construction of the membrane have been studied, along with the experimental variables related to the fixation process of the analyte in the membrane. The calibration graph was linear over the range 0.1–2.0 mg/L with a detection limit of 0.03 mg/L and a precision of 0.5%. The method was applied to samples of human urine and cow's milk, with recovery percentages ranging between 100.0 and 102.8%.