The Research Of High Performance Capillary Electrophoresis Methods For Cosmetic And Food Detection

With the improvement of living standards,the safety of food and cosmetics has attracted widespread attention.Some low-dose food and cosmetic additives can be added to food and cosmetics as colorants,fungicides and preservatives.However,excessive additives and prohibited components are not allowed in the field of food and cosmetics.Capillary electrophoresis(CE)has become the most important technologies because of the advantages of fast,low cost,high efficiency and environmental friendliness.In this paper,the application of CE in food and cosmetic analysis was explored.According to the characteristics of samples,different CE modes were selected and different methods for the separation and analysis of additives in food and cosmetics were established.The main contents are as follows:In Chapter 1,the basic principle of capillary electrophoresis,its separation mode and on-line enrichment technology are introduced.Meanwhile,the detection and application of capillary electrophoresis to the content of additives in food and cosmetics were described.In Chapter 2,micellar electrokinetic capillary chromatography(MEKC)was established for the determination of 1,7-naphthalenediol,2,3-naphthalenediol,1,5-naphthalenediol and 2,7-naphthalenediol in cosmetic and then compared with HPLC method.Under the optimal conditions,the separation was completed less than 6 min with the LOD of 0.070?0.19 ?g/m L and LOQ of 0.23?0.63 ?g/m L.The method has been successfully applied to the determination of the four naphthalenediols in lotion,loose powder and sun cream.Compared with the HPLC-UV method specified in the national standard,the analytical time of the four naphthalenediols was much shorter(from28.11±0.24 min to 5.54±0.12 min).The MEKC method is a potential alternative.In Chapter 3,the four naphthalenediols in cosmetics were determined by sweeping-micellar electrokinetic capillary chromatography(sweeping-MEKC).The parameters affecting the sweeping-MEKC method were optimized.Under the optimal conditions of enrichment and separation,the enrichment factor(EF)was in the range of 29?56.The LODs and LOQs of the four naphthalenediols are 0.0045?0.0094 ?g/m L and 0.015?0.31 ?g/m L.The method has been successfully applied to the determination of the four naphthalenols in foundation,sun cream and lotion.Compared with the HPLC-UV method specified in the national standard,the detection limit is equivalent and the analysis time is significantly shortened.In Chapter 4,A capillary zone electrophoresis(CZE)method was established for the detection of hexamidine diisethionate and chlorhexidine in cosmetics.Under the optimal conditions,separation achieved within 6 min.The LODs of hexamidine diisethionate and chlorhexidine were 0.14 ?g/m L and 0.26 ?g/m L respectively,and the LOQs were 0.47?g/m L and 0.87 ?g/m L respectively.This method was successfully used to detect the content of hexamidine diisethionate and chlorhexidine in cosmetics.The sample recovery was95.2%?106.0%.In Chapter 5,a method for the determination of natamycin in food by CZE combined with HPLC was developed.Several parameters affecting the CZE method were studied systematically,including the concentration of buffer solution,p H,additive and separation voltage.Under the optimal conditions,the separation was completed in 4 min with the LOD of 0.065 ?g/m L and the LOQ of 0.22 ?g/m L.The method has been successfully applied to the determination of natamycin in pastry,yogurt and peach juice.The recovery of natamycin was 96.7%?106.4%.Compared with HPLC,CZE method is easy to operate,less timeconsuming and low cost.In Chapter 6,a CZE method for the determination of dimethyl yellow and diethyl yellow in yuba was established.The concentration of buffer,p H,additive and separation voltage were optimized.Under the optimal conditions,the separation was completed in 7min.The LODs of dimethyl yellow and diethyl yellow were 0.17 ?g/m L and 0.081 ?g/m L,LOQs were 0.57 ?g/m L and 0.27 ?g/m L.The method has been successfully applied to the determination of dimethyl yellow and diethyl yellow in yuba with the recovery of93.0%?106.0%.