A novel high selective and sensitive fluorescence probe termed gatifloxacin was discovered based on fluorescence ＂on-off＂ phenomenon in the presence of Se（IV）. In the Tris-HCl/acetonitrile（3：7, volume ratio, Tris-HCl 0.05 mol/L, pH=7.3） system, the fluorescence intensity of gatifloxacin was linearly decreased with the concentration increase of Se（IV） in a range of 1.0×10-5--5.0×10-5 mol/L with a correlation coefficient of 0.9979（R2=0.9958） and in a range of 5.0×10-5--1.0 ×10-4 mol/L with a correlation coefficient of 0.9973（R2=0.9946）. The detection limit of Se（IV） was 1.70×10-6mol/L.
LIU QingHUAN YanfuZHENG QingchuanFEI QiangFEI YanqunFAN QianFENG GuodongSHAN Hongyan
Fluorescein-rhodamine 6G（Flu-Rh） was synthesized and used as the fluorescence probe for pH measurement based on fluorescence resonance energy transfer（FRET）. In the probe, fluorescein fluorophore and pH-sensitive rhodamine 6G hydrazide were used as FRET donor and acceptor, respectively. The values of acidity constant（pKa） and fluorescence quantum yield（Ф） of Flu-Rh were 3.71 and 0.72, respectively. The fluorescence efficiency of Flu-Rh remains almost constant when the pH value of the sample solution changed 10 times in a range of 4.78-7.03 continuously. The present probe is simple and easy-to-use for the pH measurement in acidic media.
A novel method for rapid,accurate and nondestructive determination of trimethoprim in complex matrix was presented.Near-infrared spectroscopy coupled with multivariate calibration（partial least-squares and artificial neural networks） was applied in the experiment.The variable selection process based on a modified genetic algorithm with fixed number of selected variables was proceeded,which can reduce the training time and enhance the predictive ability when coupled with artificial neural network model.
