Research On The Separation Of Anions By Capillary Electrophoresis And Its Application In Food Analysis

The detection of inorganic and organic anions in foods have been paid so many attentions over years, due to their siginificant influents not only on the colour, flavor, and taste of food, but also on the nutrition and dietary effect. As predominant methods, ion chromatography (IC) and high performance liquid chromatography (HPLC) have exerted an essential function in ion analysis, whereas they are not only less torlerance of complex matrices, but also cost so much time for separation. However, advantages of capillary electrophoresis (CE) in ion separation and determination have been more and more emerged to supersede older methodologied, including high efficiency, fast speed, minimum sample pretreatment, small sample and reagents consumptions, less pollution towards environment and so on. In order to strengthen the application of CE in food analysis and develop analysis methods of anions for ensure food safety, this thesis has established CE methods for deternimtion of polyphophates, organic acids and amino acids and applied to real samples. Specific results are as follows:1. The abuse of polyphosphates in aquatic culture was becoming a serious food safety problem. But it was difficulty to detect the amount of polyphosphates in aquatic products,due to the rapid decomposition of polyphosphates in aquatic products by the hydrolase during pretreatment. A method of which could inhibit the enzyme was necessary. In this dissertation, ultra high pressure (UHP) was used as a pretreatment to inactive enzyme. Pyrophosphate, tripolyphosphate and trimetaphosphates were detected by capillary zone electrophoresis (CZE). The CZE method was optimized with a running buffer of16mmol/L phosphate-8mmol/L citric acid,10mmol/L ATP and0.1mmol/L CTAB. Validation parameters of the method were considered. The ruselts showed that UHP was benefited for providing more stable and accuracy results. Polyphophates were separated less than6minutes. Good linearity of quantitative analysis was achieved within30～200mg/L, and the recoveries from frozen shrimp were79%～105%with the RSD less than7%.2.The study for the separation of eight low weight organic acids by field-amplified sample stacking coupled with CZE-direct UV detection was described. With20mmol/L borate as the carrier electrolyte,20%methanol and0.2mmol/L Ca2+as the complexing additive agents,0.1 mmol/L CTAB as electroosmotic flow modifier, samples were fitered and degassed prior to analysis, all organic acids were separated in6minutes. The proposed method was successfully applied for the rapid CZE determination of trace organic acids in honeys, the recoveries from one kind of honey was79%～100%with the RSD less than8.5%. The results showed that the contents of the organic acids among the seven honeys were different from each other.3. The separation and determination of six amino acids without derivation has been investgated by CZE-indirect UV detection. The electrophoretic conditions were optimized with the running buffer of10mmol/L phophate,0.1mmol/L CTAB,10mmol/L phthalate as background absorbance provider. The method has been successfully applied to quantitative measurement of amino acid in Zhejiang rose vinegar and the results were satisfactory.