Novel Methods Were Proposed For The Determination Of Trace Fluoroquinolones And Their Application In Milk

Chapter 1: Fluoroquinolones drug are the third generation of the Quinolones drug including Ciprofloxacin ( CIP ), Ofloxacin ( OF ) and Norfloxacin ( NRF ) etc. At present, they are wildly used since their broad antibacterial spectrum, strong antibacterial activity, high blood concentrations and so on. With the development of animal husbandry, it is not only used in clinic, but also in a variety of treatment and prevention of the animals, which promotes the growth and increases feed conversion efficiency. Residues of these drugs prototypes and their metabolites were accumulated and stored in animal cells tissues, organs and edible animal tissue (such as eggs and milk) . The residues could enter the body with the food chain, which was a potential threat for human health. So, developing an effective, simple, and rapid method for determination of the residues of Fluoroquinolones drug in animal products is of important practical significance.Chapter 2: A new co-luminescence system of CIP + Al ( III ) + La ( III ) + CTMAB ( Cetyltrimethylammonium Bromide ) was discovered, and this enhanced fluorescence spectra were studied. The fluorescence of CIP enhanced visibly by adding Al ( III ) and La ( III ) in HAc - NaAc buffer solution and the presence of CTMAB. A novel fluorescence method for the determination of trace Ciprofloxacin ( CIP ) was proposed based on the co-luminescence system.There was a linear relationship between the enhanced fluorescence intensity and the concentration of CIP in the range of 0.50 ~ 80.2μg·L-1 under the optimized condition. A novel enhanced fluorescence method for the determination of trace CIP was established by using this co–luminescence system. The detection limit of the proposed method was 0.17μg·L-1 for CIP. This method is simple, rapid and sensitive. The CIP in milk samples were analyzed by the proposed method with satisfactory results. The relative standard deviations and the recoveries were in ranges of 3.21% ~ 4.34% and 97.1% ~ 100.1%, respectively. The mechanism of the co-luminescence reaction and the reasons for fluorescence enhancement have been discussed.Chapter 3: A novel fluorescence method was proposed for the determination of trace CIP and OF based on the fluorescence properities of CIP and OF, synchronous fluorescence technonogy and dual-wavelength method. In pH 4.8 HAc-NaAc buffer solution, the general fluorescence spectra of CIP and OF are overlapped seriously. The resolving power of synchronous fluorescence spectra of CIP and OF in admixture solution could be improved by using synchronous scanning technonogy. In accordance with their characteristics of synchronous fluorescence spectra, the dual-wavelength method could be used to reduce the mutual interference and improve the accuracy of determination results.Under optimal conditions, when CIP was determianted, measure wavelength and reference wavelength were 438 and 526 nm, respectively, the linear range between the increased value of fluorescence intensity (ΔF ) and the CIP concentrations were 1.66 ~ 165.5μg·L-1, and the detection limits was 1.14μg·L-1. When OF was determinated, measure wavelength and reference wavelength were 429 and 400 nm, respectively, the linear range between the increased value of fluorescence intensity (ΔF ) and the OF concentrations were 2.08 ~ 208μg·L-1, and the detection limits was 1.54μg·L-1. The new synchronous fluorescence - dual wavelength method was used to determine simultaneously residues of ciprofloxacin and ofloxacin in milk samples. The characteristics of this method is high accuracy, strong anti-interference ability, simple operation and low detection limit.Chapter 4: A novel Resonance Rayleigh scattering ( RRS ) method was proposed for the determination of trace NRF. This new method is based on in HCl media, Bi ( III ) was reacted with I- to form the complex ion ( [ BiI4 ]- ), and then the [ BiI4 ]- further associate with cation NRFH+ to form the ion-association which resulting in forming the new RRS spectra and enhanceing significantly of RRS. The maximum RRS wavelength is located at 469 nm.Under the optimum condition, the determination linear range and the detection limits of this method are 3.2 ~ 1.3×102μg·L-1 and 0.96μg·L-1 for NRF, respectively. This method is simple, sensitive. The NRF in milk samples were analyzed by the proposed method with satisfactory results.Chapter 5: In HCl media, Bi ( III ) could react with Cl- to form the complex ion (Ⅲ). The [BiCl4 ]- would associate further with CIP to form the ion-association complex which resulting in enhancing significantly of RRS. The maximum RRS wavelength is located at 469 nm. Based on this, a novel RRS method for the determination of trace CIP was proposed.Under the optimum condition, the linear ranges between the increased value of fluorescence intensity (ΔI ) and the concentrations of CIP were 3.2 ~ 1.3×102μg·L-1, and the detection limits was 0.96μg·L-1for CIP. This method is simple and sensitive. The CIP in milk samples were analyzed by the proposed method with satisfactory results.