Study Of Fuoroquinolone Antibiotics By Direct Mass Spectrometry Analysis

With the extensive and intensive use of fluoroquinolone antibiotics, a lot of adverse effects, such as counterfeit antibiotics, antibiotics residues in environment, have been increasingly raising concerns. Considering the adverse effects accompanied with large-scale use of fluoroquinolone antibiotics, not only great efforts of all sectors of society should be paid to address the current situation of antibiotic abuse, more importantly, is to improve detection methods and testing standards of fluoroquinolone antibiotics. Representative techniques including microbiological assay, immunoassay, nuclear magnetic resonance, chromatography, other coupling techniques and etc. have been employed for antibiotics analysis. With the emergence of new mass spectrometry technologies, the advantages of no sample pretreatment, rapid analysis and high sensitivity are conducive to make high-throughput analysis into fact. Besides, combined with small mass spectrometer, they are expected to be used for the online analysis of samples with complex matrices to achieve the real-time, online and high-throughput analysis.Based on the brief overview of fluoroquinolone antibiotics’ recent use status and common analytical testing methods, and combined with the development of new mass spectrometry, this thesis mainly build the rapid analysis of fluoroquinolone antibiotics with complex matrix by surface desorption atmospheric pressure chemical ionization(DAPCI) and extractive electrospray ionization(EESI).The main contents of this thesis are as follows:1. Briefly introduce the principle, characteristics and common ionization device of DAPCI and EESI.2. To investigate the fragmentation mechanism of fluroquinolones, five compounds of fluroquinolones were analyzed using surface desorption atomospheric pressure chemical ionization mass spectrometry by collision induced dissociation in positive ion detection mode. The mass spectra and structures of the five fluroquinolones were compared with each other, and then the possible structure change and fragmentation mechanism were given; studies have shown that fluoroquinolone antibiotics in a complex matrix samples(food, medicine, water) can be quickly analyzed by DAPCI-MS, without any sample preparation; DAPCI-MS, as a non-polluting, non-toxic, in-situ, non-destructive, rapid analytical methods, provides a new way for the fast analysis of pharmaceuticals with a complex matrix.3. A method for rapid determination of norfloxacin was developed by EESI-MS. Ganjiang water was directly analyzed after simple filtration, and the mass spectra were recorded using optimized experimental parameters. Under the positive ion detection mode,tandem MS was applied and fragmentation characteristics of norfloxacin were observed when the ionized molecules(m/z 320) was mass-selected and subjected to collision-induced dissociation(CID). The third mass spectra m/z 256 produced by tandem mass spectrometry was used to discharge false positives. Less than 1 min was need for a single sample’s measurement, besides, average recoveries were 86.5% and 79.2%, respectively, and the relative standard deviation(RSD) was 1.25% and 1.12%, respectively. The detection limit of norfloxacin in Gan jiang River is 1.53 μg/L, established a rapid mass spectrometry method to detect norfloxacin in environmental water sample.