The resonance Rayleigh scattering spectra of the interactions for cerium(IV) with fluoroquinolone antibiotics and their analytical applications

Abstract

In pH 4.0-5.0 faintly acid media,fluoroquinolone antibiotics(FLQs)such as norfloxacin(NOR),ciprofloxacin(CIP),pefloxacin(PE),lomefloxacin(LOM)and sparfloxacin(SPA),react with Ce(Ⅳ)to form Ce(HL)(OH)4 ternary chelation complexes.Those can result in slightly changes of the absorption spectra and a small increase of their molar absorptivities.Furthermore,the reactions can result in the enhancement of resonance Rayleigh scattering(RRS).The maxinum scattering peaks of five systems are located near 381 nm,and there is a smaller RRS peak near 534 nm.The intensity of RRS is directly proportional to the concentration of fluoroquinolone antibiotics in the certain range for all systems,and the RRS methods have the high sensitivities.The detection limits for fluoroquinolone antibiotics in the range of 1.9-5.3 ng mL-1 for the other four systems,ecxept for sparfloxacin-Ce(Ⅳ) system(which is 16.0 ng mL-1).In this work,we investigated the spectral characteristics of RRS,the optimum conditions of the reactions,and the properties of the analytical chemistry.In addition,the enhancement reasons of RRS and the mechanism of reactions were discussed by the absorption spectra and quantum chemistry calculating with density function theory(DFT)at B3LYP/6-31g(d)level.