Study On New Methods For The Determination Of Norfloxacin And Lomefloxacin Residue In Milk And Their Applications

Chapter1The current research progress and the health inspection significanceof norfloxacin and lomefloxacin residual were introduced, respectively. The basicprinciples and quantitative determination basis for inhibition fluorescence quenchingmethod and resonance Rayleigh light scattering method were also introduced brieflyin this topic.Chapter2In neutral buffer (pH7.0) solution, acridine orange (AO) canreaction with AR to form a complex, which results in the energy transfer betweenthem and the fluorescence reducing of AO. When LFLX was added in this solutionthe fluorescence of AO was enhanced, because LFLX can combine with AR to formthe stable complexe and to inhibition the energy transfer. Based on this, an inhibitionfluorescence quenching method for determination of LFLX was established. Therewas a nice liner relationship between fluorescence enhancement value ΔF and LFLXconcentration in the concentration range of4.86×10-8~3.95×10-6mol·L-1at λem=530nm. The Linear regression equation was ΔF=198.7+1052.3c (×10-6mol·L-1), thedetection limit was1.46×10-8mol·L-1, and the RSD were2.34%and1.13%. Thestandard addition recoveries of milk sample were98.84%~104.33%.Chapter3The fluorescence intensity of Rhodamine6G (Rh6G) was reduced,even disappear, when Rh6G combined with alizarin red (AR) in a ratio of1:1in thecitric acid-NaOH buffer system. The adding of NFLX would result in the enhancingof fluorescence intensity of the solution becsues the NFLX-AR complex formed in thesolution prevented the combined reaction between Rh6G and AR. Accordingly, aninhibition fluorescence quenching method for determination of NFLX was established.The concentration range of the liner relationship between ΔF and NFLX concentrations was9.9×10-8~2.8×10-6mol·L-1. The detection limit of NFLX was2.97×10-8mol·L-1and RSD was less than2.61%. The recoveries of standard additionof milk sample were in the range of96.53%~103.2%.Chapter4A novel method for the determination of LFLX was developed basedon the enhancement of Rayleigh Ligth scattering (RLS) of the Cu2+-LFLX-EB systemin the BR buffer system. The maximum RLS wavelength was at380nm. Under theoptimum condition, the determination liner range was2.81×10-8~8.40×10-6mol·L-1forLFLX. The Linear regression equation was ΔI=9.94+143c (×10-6mol·L-1). Thedetection limit for LFLX was8.43×10-9mol·L-1, and the RSD were1.28%~2.34%.This method is simple, and has high precision，good accuracy and the low detectionlimit. The recoveries were in the range of95.33%~102.8%. Used in the detection ofLFLX in milk, the result was satisfactory.