Study Of High Sensitivity Analysis Method Of Typical Antibiotics In Waters By Capillary Electrophoresis

The pollution of antibiotics in environmental have been a widely concerned problem.China is one of the most abused countries in the world.Antibiotics are frequently detected in environmental water sources of China such as river water,lake water and even drinking water,influence ecological environment and human health,it's significant to assess the risk of antibiotics residue in environmental water?generally in the?g/Lⁿg/L range?with a efficient high sensitive detection method.Capillary electrophoresis?CE?as a new and powerful chromatography technique has advantages of high resolving power,short analysis time,less solvent consumption and flexible separation models,which could be applied in many fields and even used in environment analysis.In this paper,fluoroquinolones?FQs?antibiotics and sulfonamides?SAs?antibiotics were employed as representatives of antibiotics,the separation behavior of FQs and SAs were investiged by capillary electrophoresis with UV detector.In CE,UV detector is most familiar and employed,but with a low sensitivity.In order to satisfy the determination of trace FQs and SAs in environmental water,that we need to improve the detection sensitivity.In view of this experiment,both FQs and SAs are in the form of anion,so as to introduce a larger amount of analytes and accelerate the separation time in the process of electrokinetic injection?EKI?,we study the reversal of electroosmotic flow?EOF?in detail.In addition,on the basis of reversed EOF,high sensitive analytical methods of seven antibiotics were developed by applying CE on-line stacking of electrokinetic supercharging?EKS?.Chapter one:Firstly,the basic principles,instrument structure,separation mode,and enrichment methods of CE were introduced briefly.Then,the current status of the use of antibiotics and the pollution of environmrnt waters was introduced,focusing on the research progress of the antibiotics and the application of capillary electrophoresis in the analysis of antibiotics.Finally,the purpose and significance of this topic were described briefly.Chapter two:seven typical antibiotics of SAs antibiotics?including sulfamethoxazole,sulfamethazine,sulfadiazine?and FQs antibiotics?including ofloxacin,norfloxacin,ciprofloxacin,enrofloxacin?were separated and detected by capillary electrophoresis with ultraviolet detector?CE-UV?under pressure injection?HDI?and EKI conditions.By studying the concentrations ofmethyl-?-cyclodextrin?M-?-CD?,and investigating the concentrations and pH of background electrolyte?BGE?,the optimized parameters were as follows:25 mM Na₂B₄O₇+15 mM M-?-CD.Other CE conditions,detection wavelength:272 nm,seperation voltage:+15 kV,HDI:0.5 psi×5s and EKI:-10 kV×6 min.Under optimal conditions,the detection limits?LODs??S/N=3?of seven antibiotics were obtained by EKI for 6 min were 6.08-9.73?g/L,that was improved by20³0 times in comparison to HDI,and the relative standard deviation?RSD?of separation time and peak area were 0.66⁰.83%and 1.47⁴.77%respectively.Chapter three:The separation behaviors of SAs and FQs antibiotics were investigated by CE with the aid of reversed EOF.In this study,hexadimethrine bromide?HDMB?was used as the reversed reagent for EOF,which was changed from+4.71×10^-44 cm²/vs to-3.37×10^-44 cm^2/vs by without and with the concentration of HDMB at 0.01%?w/v?in BGE,respectively.It was found the additive of M-?-CD in BGE benefited the separation of most of antibiotics since their different Guest-Host interaction.The optimal BGE was composed of 15 mmol/L Na₂B₄O₇+20 mmol/L M-?-CD+HDMB?0.1%,w/v?at pH 10.1?adjusted by 1.0 M NaOH?.With the help of the reserved EOF,the negatively charged antibiotics moved with the same direction of EOF,which caused short injection time but with the same sensitivity since the sample depletion would be decreased in EKI.Finally,the seven antibiotics were rapidly baseline separated within 9 mins.Their linear ranges were in the range of 2.0³00.0?g/L with all high correlation coefficients?r²?over 0.9916and the LODs?S/N=3?were 1.12².80?g/L,which was comparable of CE with fluorescence detection?FD?.The recoveries of the developed method were in the range of 82.6¹02.0%by spiking seven antibiotics in the real lake water collected in the campus.Chapter four:seven typical antibiotics were enriched and separated with using NaNO₃ as the leading electrolyte and 3-?cyclohexylamine?propanesulfonic acid?CAPS?as the terminating electrolyte by EKS.The injection time and concentration of leading and terminating electrolytes were optimized.The analytical method was validated under the optimal conditions,the LODs?S/N=3?of seven antibiotics was 0.28⁰.74?g/L.Chapter five:describes the research results and prospects of the subject.