Study For Determination Of Moxifloxacin And DNA Based On Terbium Fluorescent Complexes

Rare earth fluorescent complexes have the advantages of good chemical resistance, strong luminescent intensity, long fluorescence lifetime, narrow half-peak width of emission peak and large Stokes shift. Based on rare earth fluorescent complexes, quantitative analysis methods of the related substances have drawn wide attention of analytical researchers. Moxifloxacin (MOX) is one of the fourth generation of fluoroquinolones, because of the unique molecular structure, it has strong antimicrobial properties and wide antimicrobial spectrum. On the other hand, it is not easy to induce drug resistance. But irrational use of the drug for a long time will do great harm to the health of people. DNA is the main carrier of genetic information, quantitative determination of DNA can provide guidance to the treatment of disease and dug use in the clinical medical diagnosis. Therefore, the establishments of sensitive, accurate and simple determination methods for MOX and DNA have great significance.In the buffer solution of methenamine-HCl, which pH is 6.0, MOX could form the coordination complex with Tb3+. In the complex, MOX can absorb certain wavelength of ultraviolet light, and then transfer the energy to Tb3+. As a result, characteristic fluorescence emmision of Tb3+ was observed. Based on this phenomenon, a fluorescence method was developed for the determination of MOX. At the optimum conditions, a good linearity between the fluorescence intensity of the system and the concentration of MOX in the range of 1.00～1.00×103μg/L was obtained. The linear regression equation was ΔI=0.92c+ 3.11 (the unit of c isμg/L) with a correlation coefficient of 0.9991 and the detection limit was 0.07 μg/L, RSD was 0.2% (cMOX=5.00μg/L, n=11). The method has been applied to the determination of MOX in serum samples with the average recovery of 104%.Under appropriate conditions, Sarafloxacin(SRFX) could coordinate to Tb3+ and form binary complexes. After the addition of DNA to the aforesaid system, the fluorescence intensity could be greatly enhanced. At the optimum conditions, the enhancement of fluorescence intensity (AI) is proportional to the concentration of DNA in the range of 0.0500～7.00 mg/L. The linear regression equation was ΔI=122.04c+1.16 (the unit of c is mg/L) with a correlation coefficient of 0.9995 and the detection limit was 0.005 mg/L, RSD was 0.2% (cDNA=0.500 mg/L, n=11). The mechanism of the fluorescence enhancement effect of DNA was also discussed in this paper, and the results showed that there are electrostatic interactions and groove binding between DNA and Tb3+-SRFX.