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

The enhancing effect of thenoyltrifluoroacetone on the fluorescence in tensity of the Eu(III)-tetracycline system in the presence of Triton X -100 was studied by using equilibrium and kinetic measurements. This l igand significantly improves the sensitivity of equilibrium methods fo r tetracycline determination based on energy-transfer processes. Kinet ic methodology implemented by means of the stopped-flow mixing techniq ue allows analytical data to be acquired within 5 s after the reactant s are mixed, thereby minimizing manipulation and enabling ready applic ation of the proposed method to routin analysis for tetracycline in se rum 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 standa rd deviations were close to 1%. The mean recovery obtained in the anal ysis of serum samples was 98.8%.