Applications Of Hyphenatedcapillary Electrophoresis In The Edible Oil Analysis

Capillary electrophoresis （CE）, or called as High Performance CapillaryElectrophoresis （HPCE）, is a sort of new liquid phase separation analytical technology.With a high-voltage power supply providing electric field and a capillary tube as theseparation channel, CE separates the analytes by their different mobilities anddistribution behavior between the components of the sample. It has the advantage ofsimple operation, little sample volume, high speed, high column efficiency and lowcost. Nowadays, CE is widely used for the rapid analysis of inorganic anions andcations, biological macromolecules, neutral compounds and has been successfullyapplied in many fields, such as environmental chemistry, food chemistry, medicinalchemistry and so on, so it has a broad application prospect. In this thesis, the studies ofCE combined with ultraviolet detection （UV） for the analysis in the edible oil wereillustrated. The thesis consists of four chapter, and the main contents are described asfollows:Chapter one is the introduction. Based on extensive research of literature, theprinciple, characteristics, separation mode and applications of capillary electrophoresiswere introduced. Combined with the development trend of capillary electrophoresis,the authors put forward the research goal of this dissertation.Chapter two, based on the inhibiting effect of product of cholesterol-glacial aceticacid-ammonium ferric sulfate on the bis（2,4,6-trichlorophenyl）oxalate（TCPO）-H₂O₂-imidazole chemiluminescence （CL） reaction, a flow-injection couplingwith indirect CL detection method for the determination of cholesterol has beendeveloped. In this work, key experimental parameters for flow injection and CL wererespectively optimized. The optimal conditions of CL system were0.001mol/Limidazole,0.3mol/L H₂O₂and1.0×10-3mol/L TCPO, and peristaltic pump20r/minand sub-peristaltic pump15r/min. Under the optimum conditions, the relative CLintensity is linearly proportional to the concentration of cholesterol from8.6×10-6².2×10-4mol/L （R=0.9988）, the detection limit （S/N=3） turned out to be2.5×10-6mol/L. For the determinations （n=11） of6.5×10-5mol/L cholesterol, a relative standard deviation is calculated to be1.5%. For the determinations of real sample, the additionstandard recoveries are95.0%¹05.0%, and the relative standard deviations are below3.6%. The method has been applied to determine cholesterol in hogwash oil withsatisfactory results.Chapter three, based on the complexation reactions between metal ions andimidazole which increased differences of the ionic mobility, a method by capillaryzone electrophoresis（CZE）was developed for the determination of K+, Al3+, Pb2+, Cu2+,Zn2+. The effects of pH and concentration of running buffer, separation voltage andinjection time were investigated and optimized. The results showed that five kinds ofmetal ions could be baseline separated in a20mmol/L imidazole （pH3.8） with aseparation voltage of20KV and detection wavelength of214nm within10min.Under the optimum conditions, excellent linear response was obtained for five kinds ofmetal ions in the concentration rang from1to50mg/L with the limits of detection（S/N=3） varied from0.05to5.0mg/L. The average recoveries ranged from92.4%to101.8%while the relative standard deviations （RSD） of migration time and peak areawere0.51%¹.20%and0.92%².59%respectively. The method was efficient, fastand simple and had been applied to determine edible oil with satisfactory results.Chapter four, a method based on micellar electrokinetic capillary chromatography（MECC） was established for the simultaneous separation and determination of TertiaryButylhydroquinone （TBHQ）, Butyl hydroxy anisd （BHA）, Butylated hydroxytoluene（BHT）. In this paper, the separation conditions of pH and concentration of buffersolution, surfactant, organic modifier, separation voltage and injection time wereoptimized by using the orthogonal experimental design. The results indicated that eachcomponent detected at a wavelength of224nm could achieve baseline separationwithin15min in20mmol/L boric acid-20mmol/L Sodium dodecyl sulfate （SDS）-20%（volume fraction） acetonitrile buffer （pH9.3） with a constant voltage of20kV andpressure injection time of4s. Under the optimized conditions, the response was linearwith correlation coefficients ranging from0.9990to0.9997, recoveries from90.0%to101.0%and relative standard deviations （RSD）（n=6） ranging from1.48%to4.72%.The results confirm that the method is simple and fast and can be applied to the rapid detection of phenolic antioxidants in edible oil.