Determination Of Melamine And Related Compounds And Prediction For The Chiral Separation Efficiency Using Mass Spectrometry

This article mainly established methods for simultaneous determination of melamine and related compounds (ammeline, ammelide and cyanuric acid) in foods by capillary zone electrophoresis and hydrophilic interaction liquid chromatography-electrospray mass spectrometry; prediction for the separation efficiency of a pair of enantiomers by determining complex binding constants using electrospray ionization mass spectrometry. The established methods can provide the stable and reliable results for the determination of melamine and related compounds in foods, and provide a simple way to select the chiral selectors by determining complex binding constants, so the results of this method are intuitional and reliable.The studies in this thesis are summarized as follows:1. For the first time, a simple, rapid, and accurate method for the simultaneous determination of melamine and related compounds by capillary zone electrophoresis with diode array detection (CE-DAD) was developed and successfully applied in egg, dairy products and pet feed. After investigating the effect of pH on the UV absorption spectrum and the optimization of CE conditions, the proposed method was proved to have the merits of good stability, easy operation, short analysis time and low cost.2. A rapid method based on hydrophilic interaction liquid chromatography coupled to electrospray ionization mass spectrometry (HILIC/ESI-MS) for the quantitative determination of melamine and its related compounds in foods has been developed and validated. We investigated effects of different mobile phases and interplay of analytes on electrospray ionization efficiency of analytes, and it is proved that ESI-MS responses of the analytes in HILIC mobile phase are better than that in RP-HPLC mobile phase and that the baseline separation of analytes before ESI-MS detection is pre-requisite to obtain the reliable quantitative result. Then the conditions of HPLC and ESI-MS were investigated, and the target compounds were quantified using a selective ionization recording (SIR) with 15N3-melamine and 13C3-cyanuric acid being used as an internal standards. The results proved that the HILIC/ESI-MS method is satisfying and reliable and the method has merits such as high separation, sensitivity, specificity and simplicity versus the other methods reported in the literature.3. Using electrospray ionization mass spectrometry technique, a rapid, simple, and low-cost screening system for selecting the appropriate chiral selectors and prediction the eparation efficiency of a pair of enantiomers by determining complex binding constants has been developed. Then the effective mobility of each enatiomer was calculated and the binding constant was obtained by capillary electrophoresis. Compared the results of ESI-MS with CE, the reliability of ESI-MS could be evaluated. The'proposed method was used to choose the chiral selectors and predict the separation efficiency of a pair of enantiomers based on the determination of complex binding constants, and the results obtained are intuitional and reliable.