Studies On The Detemination Of Melamine And Food Additives By Capillary Electrophresis

Melamine and food additives,which are long-term excessive taken in the body and harmful to huanman health,should be monitored strictly by relevant departments.Capillary electrophoresis method is of great advantages in rapid,highly efficient separation,separation modes and less reagent and sample consumption.The separation efficiency of capillary electrophoresis could be improved by changing the microenvironment and characteristics of electrophoresis charge distribution.In this thesis,the determination methods of melamine,separation and analysis methods of food additives are mainly summarized.Melamine in eggs is determinated,multicomponent electrophoresis separation behavior of food additives in beverage is studied by using micellar electrokinetic chromatography pattern of capillary electrophoresis,series of analysis parameters and separation characteristics of melamine and food additives in capillary electrophoresis were explored to provide some new datas for the analysis of melamine and food additives.There are four chapters in this thesis as follows:In chapter 1,the principle,instrument structure,separation mode and characteristic of capillary electrophoresis methods are mainly introduced,the properties,harm and analysis methods of melamine,sorbic acid,methyl-p-hydroxybenzoate,ethyl-p-hydroxybenzoate,propyl-p-hydroxybenzoate,brilliant blue,amaranth and sunset yellow are summarized,analysis application of melamine and food additives are systematically expounded in the capillary electrophoresis,the main research content and significance have been proposed.In chapter 2,a capillary electrophoresis ultra visible method was established for the determination of melamine in eggs.The effects of pH,concentration of buffer solutions,and the operation voltage were investigated on the separation of melamine.When the composition of 20 mmol/L formic acid and 20 mmol/L ammonium formate(pH = 3.0)worked as the buffer,in a capillary with an effective length of 41 cm and an inner diameter of 50 ?m,on which a voltage of 25 kV was applied,melamine separation was achieved within 2 minutes.Under these conditions,the linear range of 1-100?g/mL,the detection limit of 0.7 ?g/mL(S/N = 3),the standard addition recovery rate of 95%are obtained,and the relative standard deviation is less than 2%.In chapter 3,a method for the detection of preservatives such as sorbic acid,methyl-p-hydroxybenzoate,ethyl-p-hydroxybenzoate,propyl-p-hydroxybenzoate at same time by capillary electrophoresis was developed.When the composition of 20 mmol/L H3B03-Na2B4O7(pH = 10.0)worked as the buffer,in a capillary with an effective length of 41cm and an inner diameter of 50 ?m,on which a voltage of 15 kV was applied,the four kind of preservatives separation was achieved within 9 minutes.Under these conditions,the analyte peak area was linearly proportional to its concentration within the range of 10?1000 mg/L,the recovery is in the range of 95.4%~103.7%,and the relative standard deviation are less than 4.4%.The experiments showed that this method is a desirable approach for the analysis of preservatives in beverage with good reproducibility and strong specificity.In chapter 4,a method for the detection of colorants such as brilliant blue,amaranth and sunset yellow at same time by capillary electrophoresis was developed.When the composition of 15 mmol/L H3B03-Na2B4O7(pH = 10.0)worked as the buffer,30 mmol/L hydroxypropyl-?-cyclodextrin used as additive,in a capillary with an effective length of 41cm and an inner diameter of 50 m,on which a voltage of 17 kV was applied,the three kind of colorants separation was achieved within 6 minutes.Under these conditions,the analyte peak area was linearly proportional to its concentration within the range of 10?300 mg/L,the recovery is in the range of 97.7%?104.5%,and the relative standard deviation are less than 1.7%.The experiments showed this method is a desirable approach for the analysis of colorants in beverage with good reproducibility and strong specificity.