STUDY OF THE EU(III)-TETRACYCLINE-THENOYLTRIFLUOROACETONE SYSTEM BY USING THE STOPPED-FLOW MIXING TECHNIQUE - DETERMINATION OF TETRACYCLINE IN SERUM

The enhancing effect of thenoyltrifluoroacetone on the fluorescence intensity of the Eu(III)-tetracycline system in the presence of Triton X-100 was studied by using equilibrium and kinetic measurements. This ligand significantly improves the sensitivity of equilibrium methods for tetracycline determination based on energy-transfer processes. Kinetic methodology implemented by means of the stopped-flow mixing technique allows analytical data to be acquired within 5 s after the reactants are mixed, thereby minimizing manipulation and enabling ready application of the proposed method to routin analysis for tetracycline in serum samples. The calibration graphy was linear over the range 20-1000 ng ml(-1), but can be expanded up to 10000 ng ml(-1) by increasing the reagent concentrations. The within- and between-assay relative standard deviations were close to 1%. The mean recovery obtained in the analysis of serum samples was 98.8%.