Study Of Europium Fluorescent Complexes And Determination Of Lomefloxacin And Furosemide

Rare-earth fluorescent complexes have the advantages of large Stokes shift, high fluorescent emission intensity, narrow half-peak width, long fluorescent lifetime and low toxicity. Using rare-earth fluorescent complexes could establish sensitive and accurate analytical methods of ligands. The technology of pharmaceutical analysis takes an important role in medical investigation. On the one hand, determination is an important guarantee for the drug quality; on the other hand, pharmaceutical analysis in biological samples, such as urine and blood, can provide an important basis for the research of drug delivery, drug absorption and metabolism, as well as side effects on the human body.A time-resolved fluorescence analysis method was developed using europium ion as fluorescent probe for the determination of lomefloxacin (LMX) based on columinescence effect of Eu3+-La3+-LMX-SDS system. Effects of experimental conditions on the fluorescent intensity were discussed. At the optimum conditions, a good linearity between the fluorescent intensity of system and the concentration of LMX in the range of 5.00×10-7～1.00×10-5 mol/L was obtained. The linear regression equation was△I=-37.08+7.435c(×10-7 mol/L) with a correlation coefficient of 0.9990 and the detection limit was 6.8×10-8 mol/L. The method had been applied to the determination of LMX in tablets. The results agreed with that obtained via standard method in codex. The method had also been applied to the determination of LMX in urine samples with RSD between 1.2% and 1.8% and recoveries in the range of 94.0-104%. The result of the experiment showed that the method was accurate and reliable. Studies on the fluorescence enhancement of La3+ and SDS were discussed in this paper.In the presence of Triton X-100, the europium ion, furosemide (FR) and trioctylphosphine oxide (TOPO) formed ternary fluorescent complex, and the reaction mechanism was discussed. At the optimum conditions, a good linearity between the fluorescent intensity and the concentration of FR in the range of 1.00×10-7～6.00×10-6 mol/L for low concentration and 6.00×10-6～5.00×10-5 mol/L for high concentration were obtained. The linear regression equations were△I= 13.79+6.122c(×10-7 mol/L) for low concentration and△I=295.9+4.739c (×10-6mol/L) for high concentration with a correlation coefficient of 0.9957 and 0.9970. The detection limit was 6.6×10-8 mol/L. The method had been applied to the determination of FR in tablets. The results were well coincident with that obtained via standard method in codex. The method had also been applied to the determination of FR in urine samples with recoveries of 93.3-103%. Studies on the fluorescence enhancement of TOPO and Triton X-100 were analyzed in this paper.