Study On The Carcinogen 3-chloro-1, 2-propanediol By Capillary Electrophoresis

The thesis includes three parts: 1. Determination of 3-chloro-1, 2-propanediol in soy sauces by capillary electrophoresis with electrochemical detection. 2. Determination of rate constants and activation energy of 3-chloro-1,2-propanediol hydrolysis by capillary electrophoresis with electrochemical detection 3. Study on the elimination of 3-chloro-1,2-propanediol in hydrolyzed vegetable protein by capillary electrophoresis with electrochemical detection.In chapter 1, the capillary electrophoresis technique with electrochemical detection (CE-ED) for determination of 3-chloro-1,2-propanediol (3-MCPD) in soy sauces was described. Effects of several factors, such as the pH value and the concentration of the running buffer, separation voltage, injection time and the potential applied to the working electrode, were investigated to find the optimum conditions. With a 50 cm length of 25μm diameter fused-silica capillary, well-defined separation of 3-chloro-1,2-propanediol from propanediol and glycerol was achieved in 30 mmol/L borax (pH 9.24) within 13 min. Operated in a wall-jet configuration, a 0.45 mm copper-disk electrode used as the working electrode exhibits good response at 0.65 V (vs. SCE) for the analytes in 0.05 mol/l sodium hydroxide solution. The linear range for 3-MCPD was from 2.0×10-4 g/ml to 6.6×10-6 g/ml. Notably, detection limit (S/N=3) of 1.3×10-7 g/ml for 3-chloro-1,2-propanediol coincides with the criterion of food safety. This method was successfully used in the rapid analysis of 3-MCPD in soy samples. The average recoveries of 93.8-107.7% indicated that the experimental results were satisfactory.In chapter 2, the method based on capillary electrophoresis with electrochemical detection (CE-ED) to calculate the rate constants and activation energy of 3-MCPD hydrolysis was described. Operated in the optimum conditions, which were studied in chapter 1, the rate constants of 3-MCPD hydrolysis at different temperatures were determined by monitoring the concentration changes of 3-MCPD. At 80℃, 85℃and 90℃, the measured rate constants of 3-MCPD hydrolysis were 3.8×10-3 min-1, 7.1×10-3 min-1 and 11.5×10-3 min-1, respectively. The activation energy for 3-MCPD hydrolysis was calculated to be 118.1 k J/mol, which is in good agreement with the value in the literature.In chapter 3, the method to eliminate 3-chloro-1, 2-propanediol in hydrolyzed vegetable protein by capillary electrophoresis with electrochemical detection was studied in this work. The optimum condition to determine 3-MCPD in hydrolyzed vegetable protein was investigated. Operated in the optimum conditions, which were studied in chapter 1, the effects of pH value, temperature and hydrolysis time on elimination of 3-chloro-1,2-propanediol in...