The Exploration Of High Performance Capillary Electrophoresis Method For Food And Drug Analysis

Capillary electrophoresis （CE） is a field that continues to grow. It is a powerfulseparation technique, offering highefficiency, complementary selectivity and shorteranalysis time when compared with other separation methods. CE has now drawn intensiveattention during the last decades because this analytical technique offers a number ofdifferent separation formats suited to the analysis of different classes of analytes. CE iswidely used in a wide variety of fields including food analysis, molecular biology,medicine analysis and environmental monitoring. Its current main development directionis the development and perfection of the technique and applied research.In chapter1, the history of CE, the basic theories and the separation modes of CE arebriefly introduced. The application of CE in food and medicine fields has been reviewed.The goal and significance are introduced too.In chapter2, dispersive liquid–liquid microextraction （DLLME） has been proposedfor the extraction and preconcentration of Imazalil （IMZ）, Prochloraz （PZ） andThiabendazole （TBZ） fungicides in fruits and juice samples, followed by theirdetermination by nonaqueous capillary electrophoresis （NACE） with UV detection. Theseparation buffer consisted of methanol–acetonitrile （35:65, v/v） mixture containing30mmol/L amonium chloride and0.5%phosphoric acid. Several parameters of the DLLMEprocedure （such as type and volume of extraction and dispersive solvents, pH, saltaddition, and extraction time） were optimized. The optimum DLLME conditions were80μL of trichloromethane （CHCl3, the extraction solvent）,0.5mL of tetrahydrofuran （THF,the disperser solvent）, sample solution pH at6.0,5%（w/v） of sodium chloride and10s ofthe extraction time. Recoveries obtained for samples （apple, cherry tomatoes and grapejuice） at three different concentration levels, ranged from72%to102%, with relativestandard deviations （RSD） lower than6.4%. The limits of detection ranged from4.67to7.19ng/mL. In chapter3, formaldehyde in aquatic products was determined by micellarelectrokinetic capillary chromatography （MEKC） after derivatization with2,4-dinitrophenylhydrazine. Separation was carried out at25oC and25kV, using a fusedsilica capillary （75μm internal diameter,50.5cm effective length） and a UV detector setat360nm. The optimal background electrolyte was20mmol/L sodium tetraborate and20mmol/L SDS at pH9.0with3s hydrodynamic injection at30mbar. Electrophoreticanalysis took approximately6.5min. The correlation coefficients of the calibration curvewas0.9990over the concentration range2.0～100.0mg/L, and the LOD and LOQ valueswere0.57and1.89μg/ml, respectively. The recoveries were from83.7%to97.2%withsteam distillation as the sample pretreatment method.In chapter4, a capillary electrophoresis （CE） method was proposed with theapplication of response surface methodology （RSM） and artificial neural network （ANN）for the determination of amiloride hydrochloride （AM） and furosemide （FUR） inCompound Furosemide Tablets. Box-Behnken design （BBD） of RSM was used for theoptimization of CE experimental conditions. Statistical models were constructed byBox-Behnken design as well as artificial neural network using the three selected variables（buffer concentration, buffer pH and voltage）. Optimal separation conditions obtainedwere16mmol/L NaH₂PO₄buffer, pH7.21,24kV applied voltage,6s hydrodynamicinjection at30mbar, and UV detection at223nm. Electrophoretic Analysis wascompleted in less than5min, with LODs of0.31μg/mL for AM and0.66μg/mL for FUR.The method was successfully applied to determine AM and FUR in CompoundFurosemide Tablets with RSD lower than2.2%, and the recovery from98.8%to102.5%.Comparative experiments were also carried out using HPLC method described in ChinesePharmacopoeia. The validation results of the two methods are comparable, but the analysistime and reagent consumption for the proposed CE method were decreased significantly.In chapter5, the separation and determination of mebendazole and levamisolehydrochloride in Compound Mebendazole Tablets by capillary zone electrophoresis （CZE）was developed and validated. Separation was performed in a60cm （50.5cm to detectionwindow）×75μm internal diameter fused silica capillary using a background electrolyte of NaH₂PO₄（20mmol/L, pH3.0） at25kV. Good separation was obtained in less than8min. The limit of quantification for levamisole hydrochloride and mebendazole were1.43and2.50μg/mL, respectively, and calibration curves were linear from10to500μg/mLwith R²greater than0.999. Mean recoveries of the Analytes were greater than96%. Inaddition, a comparison with the LC method described in Chinese Pharmacopoeia （2010, II）demonstrated that the developed CZE method was comparable with regard to linearity,sensitivity, precision and accuracy, but the Analysis time and reagent consumption weredecreased. It should be an effective and low-cost alternative to LC method.In chapter6, a non-aqueous capillary electrophoresis （NACE） method was employedfor the separation of mebendazole and levamisole hydrochloride in CompoundMebendazole Tablets. The optimum separation in NACE, by measuring at210nm, wasobtained in a60cm （50.5cm effective length）×75μm capillary using a nonaqueoussolution system of40:60（v/v） methanol-acetonitrile containing10mmol/L amoniumchloride, and applied voltage of25kV with hydrodynamic injection. The migration timeof levamisole hydrochloride and mebendazole are2.67min and3.82min, respectively.The linearity of the method was evaluated from5to200μg/mL for each analyte and thecorrelation coefficient was not less than0.999. Good results were obtained for differentaspects including stability of the system, linearity, and precision. Detection limits of0.017μg/mL and0.022μg/mL were obtained for levamisole hydrochloride and mebendazole.Compared with the aqueous CE, the proposed NACE method has the advantages ofshorter separation time and lower detection limits.