Development Of Chromatographic Method Of Chiral Pesticides And Intense Sweetener And Its Applications

Nowadays,developing green pesticide has become a hotspot in the field of chemistry and environmental science,since traditional pesticides have heavily affected the environment safety.Chiral pesticide is one of the most important green pesticides because of its high efficacy,small dosage and safety to environment.However,most of chrial pesticides were raceme because of the restriction of technology and cost,which resulted in low efficacy.The key factor of developing the chrial pesticides is to establish effective way to separate and analyse chiral compounds.Capillary electrophoresis(CE),a powerful technology for enantiomeric separation,has been broadly recognized due to its advantages including simple operation,quick speed,high efficacy and low consumption of sample and solvent.However,its “dip-in” sample injection method,which has inherent defects,consequently resulting in poor accuracy and low precision.The technics based on CE need to be improved.The abuse problems of sweeteners are extremely serious,in contrast,the analysis method is so less and most of methods only could separate a kind of sweeteners,which couldn’t meet the demand of detecting the sweeteners.Hence,it is necessary to develop a method which can simultaneously detect many kinds of sweeteners.In chapter 1,we briefly introduced the background and application of the subject.First of all,the basic principle,separation mode and application research were introduced.The characteristic,present situation and chiral separation of chiral pesticide were provided,with the description of injection problems in current chiral separation technics with CE,and the advantages of quantitative capillary electrophoresis(q CE).Then,we also summarized the core-shell column(Halo),evaporative light scattering detection(ELSD)and sweeteners.In chapter 2,we introduced the chiral separation of imazalil based on cyclodextrin electrokinetic capillary chromatography.In this study,the importance of experimental parameters such as injection method,cyclodextrin concentration,p H and phosphate concentration in optimizing were investigated.The enantioseparation of imazalil was performed in 5.5 min when a 50 μm ID and 360 μm OD fused-silica capillary column with an effective length of 35 cm(50 cm total length)was employed with 15 m M phosphate(p H=2)containing 10 m M HP-γ-CD.The enantiomers/isomers of the imazalil were resolved successfully,and the Rs was 2.01.In chapter 3,we introduced enantiomeric and isomeric separation of three commonly used triazole fungicides(diniconazole,hexaconazole,and imazalil)was firstly studied based on micellar electrokinetic chromatography(MEKC)with hydroxypropyl-γ-CD(HP-γ-CD)as chiral selector.In this study,the importance of experimental parameters such as chiral selector type and concentration,SDS concentration,ratio of methanol,and separation voltage in optimizing were investigated.The simultaneous enantioseparation of diniconazole,hexaconazole,and imazalil was successfully achieved in 30 m M borate buffer(p H 9.0)containing 10 m M HP-γ-CD and 20 m M SDS with methanol(8%)was added as organic modifiers.The enantiomers/isomers of the three triazole fungicides were baseline resolved simultaneously,with good resolutions(Rs 2.12-15.2),and Peak efficiency(N)was over than 566825 plates/m.In chapter 4,the system of the automated quantitative CDEKC and automated quantitative MEKC were built combined the developed method of chiral separation in CE with the automated q CE,which could be used for the chiral separation of trizale pesticide such as diniconazole and imazalil.Both of them were successfully separated by adjusting the flow rate of syringe pump and the split ratio.Chapter 5 focused on an analytical method of detecting 5 intense sweeteners simultaneously in beverages: acesulfame-k,sodium saccharin,cyclamate,sucralose,and aspartame by reverse phase high performance liquid chromatography(RP-HPLC).The separation was carried out on a HALO column with methanol/ formic acid—triethylamine buffer solution(p H=4.5)-as mobile phase with gradient elution.The quanlification and quantitation were accomplished by an evaporative light scattering detection.The 5 sweeteners were baseline separated in 4.5 minute.The linear range was from 2 μg/m L to 500 μg/m L,with correlation coefficient greater than 0.997,detection limit of 2 μg/m L and limit of quantitation of 5 μg/m L.An average recovery was between 83.0% with 106.7% and the RSD was 0.84%-3.37%.Results indicated that the method was simple,quick,serviceable and applicable to detection of sweeteners in food and beverage,it’s also suitable for the detection of no ultraviolet absorption of sweeteners.In chapter 6,we summarized the whole project and and looked into the future perspective.The methods are applicable,which can be used for the preparation and production of pure chiral pesticides,the study of the difference R-enantiomer of chrial pesticides with S-enantiomer in biological activity,environmental behavior and biological toxicity,and the supervision of sweeteners in market.